Attempting to update (or downgrade from Public beta) made me recovery loop.

So I decided to go back from the 14.5 public release to 14.4.2 because I need a stable iOS release, but since default mode reported "you're up to date", I went recovery mode. plugged the iPhone in the Mac, hit "Update", got the file downloaded and guess what - after updating it shows the apple logo, but instead of a second progress bar: restart, force boot into recovery.

Tried 3 times already with also an official apple USB-Lightning (USBC-Lightning not near), no dice. restarts don't help.

Now I want the data to be fresh and not one month old (yes you or me are lucky I made a backup). Is there any way to get this running iOS 14.4.2 and not 14.5 public?