We also made some internal changes to the “RecordHistory” class and added two new events that are dispatched when records are rolled back. This allows developers to access and manipulate data, before and after a record history entry is reverted.
Do you still use the legacy XML format for your language files? To put it briefly and painlessly — migrate all your XML files to the XLIFF standard now! XLIFF was introduced with TYPO3 version 4.6 (almost 8 years ago!) and is the recommended format for language files since then. Using XML for language files has been classified as deprecated in TYPO3 version 10.1 and will no longer be supported in the near future. If you need a tool to converting XML language file, give the extension EXT:ew_llxml2xliff by Sebastian Fischer a try.