It’s always a good to use a dedicated computer to for your professional work and run it on a bit older OS. This year the changes in under the hood of macOS Catalina 10.15 are particularly massive and we have been warned by many manufacturers not to upgrade to Catalina yet.
We still recommend macOS Sierra 10.12 for Pro Tools users because it runs very stable and uses the old HFS file system. High Sierra introduced the new APFS file system which can lead to problems with real-time applications when you mix HFS and APFS volumes. macOS Mojave 10.14 is pretty stable as well but you need to update all your drives to AFPS to avoid issues.
Stay tuned for updates in the coming months, it can take a while until everything is smooth with Catalina.