diff --git a/src/collections/config/sanitize.ts b/src/collections/config/sanitize.ts
index c2f0f3e4b9..4fed5c9065 100644
--- a/src/collections/config/sanitize.ts
+++ b/src/collections/config/sanitize.ts
@@ -44,12 +44,7 @@ const sanitizeCollection = (config: Config, collection: CollectionConfig): Sanit
 
       if (sanitized.versions.drafts.autosave === true) sanitized.versions.drafts.autosave = {};
 
-      const versionFields = mergeBaseFields(sanitized.fields, baseVersionFields);
-
-      sanitized.fields = [
-        ...versionFields,
-        ...sanitized.fields,
-      ];
+      sanitized.fields = mergeBaseFields(sanitized.fields, baseVersionFields);
     }
 
     sanitized.versions = merge(versionCollectionDefaults, sanitized.versions);
@@ -62,17 +57,12 @@ const sanitizeCollection = (config: Config, collection: CollectionConfig): Sanit
     sanitized.upload.staticURL = sanitized.upload.staticURL || `/${sanitized.slug}`;
     sanitized.admin.useAsTitle = (sanitized.admin.useAsTitle && sanitized.admin.useAsTitle !== 'id') ? sanitized.admin.useAsTitle : 'filename';
 
-    let uploadFields = getBaseUploadFields({
+    const uploadFields = getBaseUploadFields({
       config,
       collection: sanitized,
     });
 
-    uploadFields = mergeBaseFields(sanitized.fields, uploadFields);
-
-    sanitized.fields = [
-      ...uploadFields,
-      ...sanitized.fields,
-    ];
+    sanitized.fields = mergeBaseFields(sanitized.fields, uploadFields);
   }
 
   if (sanitized.auth) {
@@ -103,12 +93,7 @@ const sanitizeCollection = (config: Config, collection: CollectionConfig): Sanit
       }
     }
 
-    authFields = mergeBaseFields(sanitized.fields, authFields);
-
-    sanitized.fields = [
-      ...authFields,
-      ...sanitized.fields,
-    ];
+    sanitized.fields = mergeBaseFields(sanitized.fields, authFields);
   }
 
   // /////////////////////////////////
diff --git a/src/fields/mergeBaseFields.ts b/src/fields/mergeBaseFields.ts
index 3a1fe39efe..ef2a43b210 100644
--- a/src/fields/mergeBaseFields.ts
+++ b/src/fields/mergeBaseFields.ts
@@ -1,14 +1,15 @@
 import merge from 'deepmerge';
+import { Field, fieldAffectsData, fieldHasSubFields, FieldWithSubFields } from './config/types';
 
-const mergeBaseFields = (fields, baseFields) => {
-  const mergedFields = [];
+const mergeBaseFields = (fields: Field[], baseFields: Field[]): Field[] => {
+  const mergedFields = [...fields || []];
 
-  if (fields) {
-    baseFields.forEach((baseField) => {
-      let matchedIndex = null;
+  baseFields.forEach((baseField) => {
+    let matchedIndex = null;
 
-      const match = fields.find((field, i) => {
-        if (field.name === baseField.name) {
+    if (fieldAffectsData(baseField)) {
+      const match = mergedFields.find((field, i) => {
+        if (fieldAffectsData(field) && field.name === baseField.name) {
           matchedIndex = i;
           return true;
         }
@@ -17,30 +18,23 @@ const mergeBaseFields = (fields, baseFields) => {
       });
 
       if (match) {
-        const matchCopy = { ...match };
-        fields.splice(matchedIndex, 1);
+        const matchCopy: Field = { ...match };
+        mergedFields.splice(matchedIndex, 1);
 
-        let mergedField = {
-          ...baseField,
-          ...matchCopy,
-        };
+        const mergedField = merge<Field>(baseField, matchCopy);
 
-        if (baseField.fields && matchCopy.fields) {
-          mergedField.fields = mergeBaseFields(matchCopy.fields, baseField.fields);
-          return mergedFields.push(mergedField);
+        if (fieldHasSubFields(baseField) && fieldHasSubFields(matchCopy)) {
+          (mergedField as FieldWithSubFields).fields = mergeBaseFields(matchCopy.fields, baseField.fields);
         }
 
-        mergedField = merge(mergedField, matchCopy, { arrayMerge: (_, source) => source });
-        return mergedFields.push(mergedField);
+        mergedFields.push(mergedField);
+      } else {
+        mergedFields.push(baseField);
       }
+    }
+  });
 
-      return mergedFields.push(baseField);
-    });
-
-    return mergedFields;
-  }
-
-  return baseFields;
+  return mergedFields;
 };
 
 export default mergeBaseFields;
diff --git a/src/globals/config/sanitize.ts b/src/globals/config/sanitize.ts
index 4e3af634a5..bd70787a50 100644
--- a/src/globals/config/sanitize.ts
+++ b/src/globals/config/sanitize.ts
@@ -44,12 +44,7 @@ const sanitizeGlobals = (collections: CollectionConfig[], globals: GlobalConfig[
 
         if (sanitizedGlobal.versions.drafts.autosave === true) sanitizedGlobal.versions.drafts.autosave = {};
 
-        const versionFields = mergeBaseFields(sanitizedGlobal.fields, baseVersionFields);
-
-        sanitizedGlobal.fields = [
-          ...versionFields,
-          ...sanitizedGlobal.fields,
-        ];
+        sanitizedGlobal.fields = mergeBaseFields(sanitizedGlobal.fields, baseVersionFields);
       }
 
       sanitizedGlobal.versions = merge(versionGlobalDefaults, sanitizedGlobal.versions);