diff --git a/libs/plugins/modifier.explode.php b/libs/plugins/modifier.explode.php
new file mode 100644
index 000000000..5186fde3d
--- /dev/null
+++ b/libs/plugins/modifier.explode.php
@@ -0,0 +1,25 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifier
+ */
+
+/**
+ * Smarty explode modifier plugin
+ * Type:     modifier
+ * Name:     explode
+ * Purpose:  split a string by a string
+ *
+ * @param string   $separator
+ * @param string   $string
+ * @param int|null $limit
+ *
+ * @return array
+ */
+function smarty_modifier_explode($separator, $string, ?int $limit = null)
+{
+    // provide $string default to prevent deprecation errors in PHP >=8.1
+    return explode($separator, $string ?? '', $limit ?? PHP_INT_MAX);
+}
diff --git a/libs/plugins/modifier.number_format.php b/libs/plugins/modifier.number_format.php
new file mode 100644
index 000000000..8c612601f
--- /dev/null
+++ b/libs/plugins/modifier.number_format.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifier
+ */
+
+/**
+ * Smarty number_format modifier plugin
+ * Type:     modifier
+ * Name:     number_format
+ * Purpose:  Format a number with grouped thousands
+ *
+ * @param float|null  $num
+ * @param int         $decimals
+ * @param string|null $decimal_separator
+ * @param string|null $thousands_separator
+ *
+ * @return string
+ */
+function smarty_modifier_number_format(?float $num, int $decimals = 0, ?string $decimal_separator = ".", ?string $thousands_separator = ",")
+{
+    // provide $num default to prevent deprecation errors in PHP >=8.1
+    return number_format($num ?? 0.0, $decimals, $decimal_separator, $thousands_separator);
+}
diff --git a/libs/plugins/shared.mb_str_replace.php b/libs/plugins/shared.mb_str_replace.php
index c6079c12d..7e85f7aae 100644
--- a/libs/plugins/shared.mb_str_replace.php
+++ b/libs/plugins/shared.mb_str_replace.php
@@ -62,7 +62,7 @@ function smarty_mb_str_replace($search, $replace, $subject, &$count = 0)
                 $replace = mb_convert_encoding($replace, $current_charset, Smarty::$_CHARSET);
             }
 
-            $parts = mb_split(preg_quote($search), $subject) ?: array();
+            $parts = mb_split(preg_quote($search), $subject ?? "") ?: array();
             // If original regex encoding was not unicode...
             if(!$reg_is_unicode) {
                 // ...restore original regex encoding to avoid breaking the system.
diff --git a/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierExplodeTest.php b/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierExplodeTest.php
new file mode 100644
index 000000000..b3b9d50eb
--- /dev/null
+++ b/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierExplodeTest.php
@@ -0,0 +1,55 @@
+<?php
+
+namespace UnitTests\TemplateSource\TagTests\PluginModifier;
+
+/**
+ * class for modifier tests
+ *
+ * @runTestsInSeparateProcess
+ * @preserveGlobalState disabled
+ * @backupStaticAttributes enabled
+ */
+class PluginModifierExplodeTest extends \PHPUnit_Smarty
+{
+    public function setUp(): void
+    {
+        $this->setUpSmarty(__DIR__);
+    }
+
+    /**
+     * @return void
+     * @throws \SmartyException
+     *
+     * @dataProvider explodeDataProvider
+     */
+    public function testExplode($template, $subject, $expectedString)
+    {
+        $this->smarty->assign('subject', $subject);
+
+        $tpl = $this->smarty->createTemplate($template);
+        $res = $this->smarty->fetch($tpl);
+
+        $this->assertEquals($expectedString, $res);
+    }
+
+    public function explodeDataProvider()
+    {
+        return [
+            'default'  => [
+                'template'      => 'string:{","|explode:$subject|json_encode}',
+                'subject'       => 'a,b,c,d',
+                'expectedString' => '["a","b","c","d"]',
+            ],
+            'withNoDelimiterFound'  => [
+                'template'      => 'string:{","|explode:$subject|json_encode}',
+                'subject'       => 'abcd',
+                'expectedString' => '["abcd"]',
+            ],
+            'withNull' => [
+                'template'      => 'string:{","|explode:$subject|json_encode}',
+                'subject'       => null,
+                'expectedString' => '[""]',
+            ],
+        ];
+    }
+}
diff --git a/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierNumberFormatTest.php b/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierNumberFormatTest.php
new file mode 100644
index 000000000..27feeac30
--- /dev/null
+++ b/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierNumberFormatTest.php
@@ -0,0 +1,59 @@
+<?php
+
+namespace UnitTests\TemplateSource\TagTests\PluginModifier;
+
+/**
+ * class for modifier tests
+ *
+ * @runTestsInSeparateProcess
+ * @preserveGlobalState disabled
+ * @backupStaticAttributes enabled
+ */
+class PluginModifierNumberFormatTest extends \PHPUnit_Smarty
+{
+    public function setUp(): void
+    {
+        $this->setUpSmarty(__DIR__);
+    }
+
+    /**
+     * @return void
+     * @throws \SmartyException
+     *
+     * @dataProvider numberFormatDataProvider
+     */
+    public function testNumberFormat($template, $subject, $expectedString)
+    {
+        $this->smarty->assign('subject', $subject);
+
+        $tpl = $this->smarty->createTemplate($template);
+
+        $this->assertEquals($expectedString, $this->smarty->fetch($tpl));
+    }
+
+    public function numberFormatDataProvider()
+    {
+        return [
+            'default'  => [
+                'template'      => 'string:{$subject|number_format}',
+                'subject'       => 12345,
+                'expectedString' => "12,345",
+            ],
+            'withDecimalDefault'  => [
+                'template'      => 'string:{$subject|number_format}',
+                'subject'       => 12345.6789,
+                'expectedString' => "12,346",
+            ],
+            'withDecimalAndExtras'  => [
+                'template'      => 'string:{$subject|number_format:2:"-":"~"}',
+                'subject'       => 12345.6789,
+                'expectedString' => "12~345-68",
+            ],
+            'withNull' => [
+                'template'      => 'string:{$subject|number_format}',
+                'subject'       => null,
+                'expectedString' => 0,
+            ],
+        ];
+    }
+}
diff --git a/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierReplaceTest.php b/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierReplaceTest.php
new file mode 100644
index 000000000..a4b6a12e7
--- /dev/null
+++ b/tests/UnitTests/TemplateSource/TagTests/PluginModifier/PluginModifierReplaceTest.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace UnitTests\TemplateSource\TagTests\PluginModifier;
+
+/**
+ * class for modifier tests
+ *
+ * @runTestsInSeparateProcess
+ * @preserveGlobalState disabled
+ * @backupStaticAttributes enabled
+ */
+class PluginModifierReplaceTest extends \PHPUnit_Smarty
+{
+    public function setUp(): void
+    {
+        $this->setUpSmarty(__DIR__);
+    }
+
+    /**
+     * @return void
+     * @throws \SmartyException
+     *
+     * @dataProvider replaceDataProvider
+     */
+    public function testReplace($template, $subject, $expectedString)
+    {
+        $this->smarty->assign('subject', $subject);
+
+        $tpl = $this->smarty->createTemplate($template);
+
+        $this->assertEquals($expectedString, $this->smarty->fetch($tpl));
+    }
+
+    public function replaceDataProvider()
+    {
+        return [
+            'default'  => [
+                'template'      => 'string:{$subject|replace:",":"-"}',
+                'subject'       => "a,b,c,d",
+                'expectedString' => "a-b-c-d",
+            ],
+            'doNothing'  => [
+                'template'      => 'string:{$subject|replace:"":""}',
+                'subject'       => "a,b,c,d",
+                'expectedString' => "a,b,c,d",
+            ],
+            'withNull' => [
+                'template'      => 'string:{$subject|replace:"":""}',
+                'subject'       => null,
+                'expectedString' => "",
+            ],
+        ];
+    }
+}