Hey @Brian299689383xw4. Welcome to the Lightroom Community. I'll help you figure this out.
In Lightroom Classic, check if this option is enabled in Preferences > Presets > Location > Store presets with this catalog.

If enabled, your presets are stored with the catalog you used before Lightroom updated. In Lightroom, go to File > Open Recent > check the names of the catalog you've used and go to each to find the presets.
To speed this up, use the spotlight search in the macOS finder & look for '.lrcat' to list all the catalog files on your computer.
If the above option is not enabled, do you recall a preset name you used? Look up the file on your computer & move it to the folder that opens up when you click on the 'Show Lightroom Develop Presets' in the menu I've shown above.
Let me know how it goes. Thanks!
Sameer K