Just as an FYI, I recently tried upgrading my ALL GOOD MacBook Pro (early 2013) running Mojave, to Catalina.
And... eye strain. It was that nasty low level type that really sneaks up on you.
Anyway, I downgraded - thank heavens I made several backups before the upgrade, and everything is back to normal. Phew.
Still, that means there's simply no new Apple gear or software that I know to be safe... and I'm now stuck on old versions of MacOS.