diff --git a/src/FileProcessor/FlexForms/Rector/v7/v6/RenderTypeFlexFormRector.php b/src/FileProcessor/FlexForms/Rector/v7/v6/RenderTypeFlexFormRector.php
index 8eda81dec..f40b31ca4 100644
--- a/src/FileProcessor/FlexForms/Rector/v7/v6/RenderTypeFlexFormRector.php
+++ b/src/FileProcessor/FlexForms/Rector/v7/v6/RenderTypeFlexFormRector.php
@@ -90,16 +90,16 @@ protected function refactorColumn(?DOMElement $configElement): void
         if ($renderModeDomElement instanceof DOMElement) {
             $renderMode = $renderModeDomElement->nodeValue;
             switch ($renderMode) {
-                case 'tree' :
+                case 'tree':
                     $renderTypeName = 'selectTree';
                     break;
-                case 'singlebox' :
+                case 'singlebox':
                     $renderTypeName = 'selectSingleBox';
                     break;
-                case 'checkbox' :
+                case 'checkbox':
                     $renderTypeName = 'selectCheckBox';
                     break;
-                default :
+                default:
                     $renderTypeName = null;
             }
 
diff --git a/src/FileProcessor/TypoScript/Conditions/GlobalVarConditionMatcher.php b/src/FileProcessor/TypoScript/Conditions/GlobalVarConditionMatcher.php
index ef9130cbe..03f0831c2 100644
--- a/src/FileProcessor/TypoScript/Conditions/GlobalVarConditionMatcher.php
+++ b/src/FileProcessor/TypoScript/Conditions/GlobalVarConditionMatcher.php
@@ -53,34 +53,34 @@ public function change(string $condition): ?string
             }
 
             switch ($type) {
-                case 'TSFE' :
+                case 'TSFE':
                     $conditions[$key][] = $this->refactorTsfe($property, $operator, $value);
                     break;
-                case 'GP' :
+                case 'GP':
                     $conditions[$key][] = $this->refactorGetPost($property, $operator, $value);
                     break;
-                case 'LIT' :
+                case 'LIT':
                     $conditions[$key][] = sprintf('"%s" %s "%s"', $value, self::OPERATOR_MAPPING[$operator], $property);
                     break;
-                case 'ENV' :
+                case 'ENV':
                     $conditions[$key][] = $this->createEnvCondition($property, $operator, $value);
                     break;
-                case 'IENV' :
+                case 'IENV':
                     $conditions[$key][] = $this->createIndependentCondition($property, $operator, $value);
                     break;
-                case 'BE_USER' :
+                case 'BE_USER':
                     $conditions[$key][] = $this->createBackendUserCondition($property, $operator, $value);
                     break;
-                case '_GET' :
+                case '_GET':
                     $conditions[$key][] = $this->refactorGet($property, $operator, $value);
                     break;
-                case 'GPmerged' :
+                case 'GPmerged':
                     $conditions[$key][] = $this->refactorGetPost($property, $operator, $value);
                     break;
-                case '_POST' :
+                case '_POST':
                     $conditions[$key][] = $this->refactorPost($property, $operator, $value);
                     break;
-                default :
+                default:
                     $conditions[$key][] = $condition;
                     break;
             }
diff --git a/src/Helper/FlexFormHelperTrait.php b/src/Helper/FlexFormHelperTrait.php
index b8934d5ca..0835963b0 100644
--- a/src/Helper/FlexFormHelperTrait.php
+++ b/src/Helper/FlexFormHelperTrait.php
@@ -21,7 +21,7 @@ protected function extractDomElementByKey(?DOMElement $element, string $key): ?D
                 continue;
             }
 
-            $itemKey = (string) $childNode->nodeName;
+            $itemKey = $childNode->nodeName;
             if ($key === $itemKey) {
                 return $childNode;
             }
diff --git a/src/Helper/TcaHelperTrait.php b/src/Helper/TcaHelperTrait.php
index d458208b2..8f3c8d1c9 100644
--- a/src/Helper/TcaHelperTrait.php
+++ b/src/Helper/TcaHelperTrait.php
@@ -172,6 +172,12 @@ private function hasRenderType(Array_ $columnItemConfigurationArray): bool
         return $renderTypeItem !== null;
     }
 
+    private function hasInternalType(Array_ $columnItemConfigurationArray): bool
+    {
+        $internalType = $this->extractArrayItemByKey($columnItemConfigurationArray, 'internal_type');
+        return $internalType !== null;
+    }
+
     private function extractColumns(Return_ $return): ?ArrayItem
     {
         return $this->extractArrayItemByKey($return->expr, 'columns');
diff --git a/src/Rector/v12/v0/tca/MigrateInternalTypeFolderToTypeFolderRector.php b/src/Rector/v12/v0/tca/MigrateInternalTypeFolderToTypeFolderRector.php
index 6e5acccbe..b396a7163 100644
--- a/src/Rector/v12/v0/tca/MigrateInternalTypeFolderToTypeFolderRector.php
+++ b/src/Rector/v12/v0/tca/MigrateInternalTypeFolderToTypeFolderRector.php
@@ -37,6 +37,12 @@ public function getRuleDefinition(): RuleDefinition
                     'internal_type' => 'folder',
                 ],
             ],
+            'bColumn' => [
+                'config' => [
+                    'type' => 'group',
+                    'internal_type' => 'db',
+                ],
+            ],
         ],
     ],
 ];
@@ -51,6 +57,11 @@ public function getRuleDefinition(): RuleDefinition
                     'type' => 'folder',
                 ],
             ],
+            'bColumn' => [
+                'config' => [
+                    'type' => 'group',
+                ],
+            ],
         ],
     ],
 ];
@@ -65,16 +76,26 @@ protected function refactorColumn(Expr $columnName, Expr $columnTca): void
             return;
         }
 
-        if (! $this->configIsOfInternalType($configArray, 'folder')) {
+        if (! $this->isConfigType($configArray, 'group') || ! $this->hasInternalType($configArray)) {
+            return;
+        }
+
+        $internalTypeArrayItem = $this->extractArrayItemByKey($configArray, 'internal_type');
+        if (! $internalTypeArrayItem instanceof ArrayItem) {
+            return;
+        }
+
+        $internalTypeValue = $this->valueResolver->getValue($internalTypeArrayItem->value);
+
+        if (! is_string($internalTypeValue)) {
             return;
         }
 
-        $toRemoveArrayItem = $this->extractArrayItemByKey($configArray, 'internal_type');
-        if ($toRemoveArrayItem instanceof ArrayItem) {
-            $this->removeNode($toRemoveArrayItem);
+        if ($internalTypeValue === 'folder') {
+            $this->changeTcaType($configArray, 'folder');
         }
 
-        $this->changeTcaType($configArray, 'folder');
+        $this->removeNode($internalTypeArrayItem);
 
         $this->hasAstBeenChanged = true;
     }
diff --git a/tests/Rector/v12/v0/tca/MigrateInternalTypeRector/Fixture/fixture.php.inc b/tests/Rector/v12/v0/tca/MigrateInternalTypeRector/Fixture/fixture.php.inc
index 9c10c8ba6..025c33ffc 100644
--- a/tests/Rector/v12/v0/tca/MigrateInternalTypeRector/Fixture/fixture.php.inc
+++ b/tests/Rector/v12/v0/tca/MigrateInternalTypeRector/Fixture/fixture.php.inc
@@ -9,6 +9,14 @@ return [
             'config' => [
                 'type' => 'group',
                 'internal_type' => 'folder',
+                'maxitems' => 2,
+            ],
+        ],
+        'bColumn' => [
+            'config' => [
+                'type' => 'group',
+                'internal_type' => 'db',
+                'minitems' => 2,
             ],
         ],
     ],
@@ -26,6 +34,13 @@ return [
         'aColumn' => [
             'config' => [
                 'type' => 'folder',
+                'maxitems' => 2,
+            ],
+        ],
+        'bColumn' => [
+            'config' => [
+                'type' => 'group',
+                'minitems' => 2,
             ],
         ],
     ],