It happened to me that I accidentaly changed metadata to many files, and it took me a lot of tome the restore them. An "undo" function would be very useful.
We may consider it in the future.
Yes, PLEASE add undo support for metadata changes. It has happened to me several times that I use the wrong keyboard shortcut when applying a star rating vs a color class (as the single keys don't work for multiple images). It does indeed take a lot of time trying to manually figure out how to undo it, and sometimes it's just not possible. I have seen it done in other DAM applications.