DI you read the following support page regarding 10.5 and Plugins?
https://support.apple.com/en-us/HT211239
As far as I understand, it is the old finger pointing game. Apple changes/updates something that requires the third-party developer to update their software (plugin). They give them prior notice to have it fixed by the release date. However, that works only in a perfect world.
In the case of Logic and Plugins, the end user can run into really annoying issues. For example, the developer didn't update in time, the developer refused to update (no time, no money, no interest), the developer doesn't exist anymore.
Hope that helps,
Edgar Rothermich
Graphically Enhanced Manuals (GEM)
www.LogicProGEM.com
https://www.youtube.com/c/MusicTechExplained/