diff --git a/.changelog/465.txt b/.changelog/465.txt
new file mode 100644
index 000000000..5e2118c37
--- /dev/null
+++ b/.changelog/465.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+internal/fwserver: Delayed deprecated attribute/block warnings for unknown values, which may be null
+```
diff --git a/internal/fwserver/attribute_validation.go b/internal/fwserver/attribute_validation.go
index 779017c2f..55808d412 100644
--- a/internal/fwserver/attribute_validation.go
+++ b/internal/fwserver/attribute_validation.go
@@ -116,25 +116,13 @@ func AttributeValidate(ctx context.Context, a fwschema.Attribute, req tfsdk.Vali
 
 	AttributeValidateNestedAttributes(ctx, a, req, resp)
 
-	if a.GetDeprecationMessage() != "" && attributeConfig != nil {
-		tfValue, err := attributeConfig.ToTerraformValue(ctx)
-		if err != nil {
-			resp.Diagnostics.AddAttributeError(
-				req.AttributePath,
-				"Attribute Validation Error",
-				"Attribute validation cannot convert value. Report this to the provider developer:\n\n"+err.Error(),
-			)
-
-			return
-		}
-
-		if !tfValue.IsNull() {
-			resp.Diagnostics.AddAttributeWarning(
-				req.AttributePath,
-				"Attribute Deprecated",
-				a.GetDeprecationMessage(),
-			)
-		}
+	// Show deprecation warnings only for known values.
+	if a.GetDeprecationMessage() != "" && !attributeConfig.IsNull() && !attributeConfig.IsUnknown() {
+		resp.Diagnostics.AddAttributeWarning(
+			req.AttributePath,
+			"Attribute Deprecated",
+			a.GetDeprecationMessage(),
+		)
 	}
 }
 
diff --git a/internal/fwserver/attribute_validation_test.go b/internal/fwserver/attribute_validation_test.go
index bc33e6565..4a966cd3c 100644
--- a/internal/fwserver/attribute_validation_test.go
+++ b/internal/fwserver/attribute_validation_test.go
@@ -488,15 +488,7 @@ func TestAttributeValidate(t *testing.T) {
 					},
 				},
 			},
-			resp: tfsdk.ValidateAttributeResponse{
-				Diagnostics: diag.Diagnostics{
-					diag.NewAttributeWarningDiagnostic(
-						path.Root("test"),
-						"Attribute Deprecated",
-						"Use something else instead.",
-					),
-				},
-			},
+			resp: tfsdk.ValidateAttributeResponse{},
 		},
 		"warnings": {
 			req: tfsdk.ValidateAttributeRequest{
diff --git a/internal/fwserver/block_validation.go b/internal/fwserver/block_validation.go
index 1f6b77d20..17e2b85af 100644
--- a/internal/fwserver/block_validation.go
+++ b/internal/fwserver/block_validation.go
@@ -195,26 +195,13 @@ func BlockValidate(ctx context.Context, b fwschema.Block, req tfsdk.ValidateAttr
 		return
 	}
 
-	if b.GetDeprecationMessage() != "" && attributeConfig != nil {
-		tfValue, err := attributeConfig.ToTerraformValue(ctx)
-
-		if err != nil {
-			resp.Diagnostics.AddAttributeError(
-				req.AttributePath,
-				"Block Validation Error",
-				"Block validation cannot convert value. Report this to the provider developer:\n\n"+err.Error(),
-			)
-
-			return
-		}
-
-		if !tfValue.IsNull() {
-			resp.Diagnostics.AddAttributeWarning(
-				req.AttributePath,
-				"Block Deprecated",
-				b.GetDeprecationMessage(),
-			)
-		}
+	// Show deprecation warning only on known values.
+	if b.GetDeprecationMessage() != "" && !attributeConfig.IsNull() && !attributeConfig.IsUnknown() {
+		resp.Diagnostics.AddAttributeWarning(
+			req.AttributePath,
+			"Block Deprecated",
+			b.GetDeprecationMessage(),
+		)
 	}
 }
 
diff --git a/internal/fwserver/block_validation_test.go b/internal/fwserver/block_validation_test.go
index 3daa259ae..e776748eb 100644
--- a/internal/fwserver/block_validation_test.go
+++ b/internal/fwserver/block_validation_test.go
@@ -178,15 +178,7 @@ func TestBlockValidate(t *testing.T) {
 					},
 				},
 			},
-			resp: tfsdk.ValidateAttributeResponse{
-				Diagnostics: diag.Diagnostics{
-					diag.NewAttributeWarningDiagnostic(
-						path.Root("test"),
-						"Block Deprecated",
-						"Use something else instead.",
-					),
-				},
-			},
+			resp: tfsdk.ValidateAttributeResponse{},
 		},
 		"warnings": {
 			req: tfsdk.ValidateAttributeRequest{