presets are lost!

https://www.lightroomqueen.com/missing-default-presets-75/

https://m.youtube.com/watch?v=mYx899_tNP8

https://blog.thomasfitzgeraldphotography.com/blog/2018/4/managing-lightroom-presets-in-lightroom-classic-73-or-later

https://mattk.com/digging-deeper-questions-new-lightroom-profiles/

What was your previous version?

Are these User Preset or Presets that you purchased? They aren't  deleted unless you physically deleted them. There are a few ways to find them. Once you find them you can move  them  to the same folder that Lightroom resides in and then check the preferences > presets > store with this catalog

Try

- navigate to them by going into your preferences > presets > Show all other presets

- navigate to them by going into your Lightroom Settings folder in the Pictures folder

- search at  the system level