Bridge - update of keywords not possible

How about details- what kind of older pics, located where, what do you mean by "does not work" specifically?

You should always wait to update your Mac operating system until you verify that the non-Apple programs you use are going to work properly... not only Adobe programs, the 2nd link below is about Avid... aimed at video editing, but it is a warning for ALL non-Apple program users
https://community.adobe.com/t5/download-install/can-i-run-my-adobe-applications-in-macos-11-big-sur/td-p/11586901?page=1
https://ymcinema.com/2020/11/15/premiere-pro-and-avid-editors-do-not-upgrade-to-macos-big-sur-yet/
https://tidbits.com/2020/11/13/big-sur-is-here-but-we-suggest-you-say-no-sir-for-now/

I do NOT know if these links will work with sur
https://macpaw.com/how-to/downgrade-from-catalina or
https://www.macworld.co.uk/how-to/mac-software/downgrade-macos-3581872/