diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a183cbf335e6..259ef7a46f70 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -272,7 +272,7 @@ jobs:
             !**/node_modules/**
 
   test-babel-8-breaking:
-    name: Test Babel 8 breaking changes on Node.js
+    name: Test Babel 8 breaking changes on
     needs: build-babel8
     strategy:
       matrix:
diff --git a/packages/babel-generator/src/generators/expressions.ts b/packages/babel-generator/src/generators/expressions.ts
index 10b382f4e3ab..28a27b2c7df3 100644
--- a/packages/babel-generator/src/generators/expressions.ts
+++ b/packages/babel-generator/src/generators/expressions.ts
@@ -190,12 +190,14 @@ export function OptionalCallExpression(
 ) {
   this.print(node.callee, node);
 
-  this.print(node.typeArguments, node); // Flow
   this.print(node.typeParameters, node); // TS
 
   if (node.optional) {
     this.token("?.");
   }
+
+  this.print(node.typeArguments, node); // Flow
+
   this.token("(");
   this.printList(node.arguments, node);
   this.token(")");
diff --git a/packages/babel-generator/src/generators/flow.ts b/packages/babel-generator/src/generators/flow.ts
index e0cb079e0179..7d037bbf321a 100644
--- a/packages/babel-generator/src/generators/flow.ts
+++ b/packages/babel-generator/src/generators/flow.ts
@@ -332,6 +332,7 @@ export function FunctionTypeAnnotation(
   if (
     parent &&
     (parent.type === "ObjectTypeCallProperty" ||
+      parent.type === "ObjectTypeInternalSlot" ||
       parent.type === "DeclareFunction" ||
       (parent.type === "ObjectTypeProperty" && parent.method))
   ) {
diff --git a/packages/babel-generator/test/fixtures/decoratorsBeforeExport/false-to-true/options.json b/packages/babel-generator/test/fixtures/decoratorsBeforeExport/false-to-true/options.json
index 5cd524b7c638..72515fd85bfe 100644
--- a/packages/babel-generator/test/fixtures/decoratorsBeforeExport/false-to-true/options.json
+++ b/packages/babel-generator/test/fixtures/decoratorsBeforeExport/false-to-true/options.json
@@ -1,5 +1,6 @@
 {
   "BABEL_8_BREAKING": false,
   "plugins": [["decorators", { "decoratorsBeforeExport": false }]],
-  "decoratorsBeforeExport": true
+  "decoratorsBeforeExport": true,
+  "expectedReParseError": true
 }
diff --git a/packages/babel-generator/test/fixtures/decoratorsBeforeExport/true-to-false/options.json b/packages/babel-generator/test/fixtures/decoratorsBeforeExport/true-to-false/options.json
index 99dc70805820..dffdbf484f18 100644
--- a/packages/babel-generator/test/fixtures/decoratorsBeforeExport/true-to-false/options.json
+++ b/packages/babel-generator/test/fixtures/decoratorsBeforeExport/true-to-false/options.json
@@ -1,5 +1,6 @@
 {
   "BABEL_8_BREAKING": false,
   "plugins": [["decorators", { "decoratorsBeforeExport": true }]],
-  "decoratorsBeforeExport": false
+  "decoratorsBeforeExport": false,
+  "expectedReParseError": true
 }
diff --git a/packages/babel-generator/test/fixtures/flow/internal-slot/output.js b/packages/babel-generator/test/fixtures/flow/internal-slot/output.js
index 3b2b5ece1a23..e4345459ab06 100644
--- a/packages/babel-generator/test/fixtures/flow/internal-slot/output.js
+++ b/packages/babel-generator/test/fixtures/flow/internal-slot/output.js
@@ -8,13 +8,13 @@ interface I1 {
   [[foo]]: X
 }
 interface I2 {
-  [[foo]]() => X
+  [[foo]](): X
 }
 type T1 = {
   [[foo]]: X
 };
 type T2 = {
-  [[foo]]() => X
+  [[foo]](): X
 };
 type T3 = {
   [[foo]]?: X
diff --git a/packages/babel-generator/test/fixtures/flow/typeapp-call/output.js b/packages/babel-generator/test/fixtures/flow/typeapp-call/output.js
index 2c2f43ea0869..6db174c9ad20 100644
--- a/packages/babel-generator/test/fixtures/flow/typeapp-call/output.js
+++ b/packages/babel-generator/test/fixtures/flow/typeapp-call/output.js
@@ -16,6 +16,6 @@ new C<T>();
 o.m<T>();
 f < T > .0;
 o?.m<T>(e);
-o.m<T>?.(e);
+o.m?.<T>(e);
 async<T>();
-f<T>?.(e);
\ No newline at end of file
+f?.<T>(e);
\ No newline at end of file
diff --git a/packages/babel-generator/test/fixtures/types/Decorator/options.json b/packages/babel-generator/test/fixtures/types/Decorator/options.json
index b4fee43f66c4..be6fc7ea6fca 100644
--- a/packages/babel-generator/test/fixtures/types/Decorator/options.json
+++ b/packages/babel-generator/test/fixtures/types/Decorator/options.json
@@ -1 +1,5 @@
-{ "plugins": ["decorators-legacy"] }
+{
+  "plugins": ["decorators-legacy"],
+  "decoratorsBeforeExport": true,
+  "BABEL_8_BREAKING": false
+}
diff --git a/packages/babel-generator/test/fixtures/types/Decorator/output.js b/packages/babel-generator/test/fixtures/types/Decorator/output.js
index db5f62ff6b7c..853583676718 100644
--- a/packages/babel-generator/test/fixtures/types/Decorator/output.js
+++ b/packages/babel-generator/test/fixtures/types/Decorator/output.js
@@ -32,15 +32,15 @@ class Foo {
 
 }
 
-export default @foo
-class Foo2 {
+@foo
+export default class Foo2 {
   bar() {
     class Baz {}
   }
 
 }
-export @foo
-class Foo3 {
+@foo
+export class Foo3 {
   bar() {
     class Baz {}
   }
diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
index b32847f2cdfe..d55ca5492a48 100644
--- a/packages/babel-generator/test/index.js
+++ b/packages/babel-generator/test/index.js
@@ -811,14 +811,15 @@ suites.forEach(function (testSuite) {
           const actualCode = actual.code;
 
           if (actualCode) {
-            const actualAst = parse(actualCode, {
+            const parserOpts = {
               filename: actual.loc,
               plugins: task.options.plugins || [],
               strictMode: task.options.strictMode === false ? false : true,
               sourceType: "module",
               sourceMaps: !!task.sourceMap,
               ...task.options.parserOpts,
-            });
+            };
+            const actualAst = parse(actualCode, parserOpts);
             const options = {
               sourceFileName: path.relative(
                 path.dirname(fileURLToPath(import.meta.url)),
@@ -832,7 +833,7 @@ suites.forEach(function (testSuite) {
               return generate(actualAst, options, actualCode);
             };
 
-            const throwMsg = task.options.throws;
+            const throwMsg = options.throws;
             if (throwMsg) {
               expect(() => run()).toThrow(
                 throwMsg === true ? undefined : throwMsg,
@@ -864,6 +865,11 @@ suites.forEach(function (testSuite) {
               } else {
                 try {
                   expect(result.code).toBe(expected.code);
+                  if (!options.expectedReParseError) {
+                    expect(() => {
+                      parse(result.code, parserOpts);
+                    }).not.toThrow();
+                  }
                 } catch (e) {
                   if (!process.env.OVERWRITE) throw e;
                   console.log(`Updated test file: ${expected.loc}`);