I have a variety of macs available to me and as of now there are no outstanding issues with USB audio on any of the T2 equipped macs that I am aware of. RME has declared the issues fixed (by Apple, with some additional workaround/mitigation on their end in the interim to help users minimize the issue). I’ve heard the same from MOTU users, though I am not one myself and would rely on others’ direct experience here to be certain - but since the issue was all related, I expect the results are the same no matter which hardware.
They were resolved by software updates from Apple directly, notably in the late 10.14 series of updates, not all at once, but IIRC 10.14.6 or so was the final point. I am unaware of any issues in any version of Catalina (save that 10.15.2 and earlier were in themselves rather buggy) and the latest version of Catalina is running perfectly on all of my systems running a wide variety of open source, closed source (including Max/MSP, Ableton Live, etc.) and personally written software.
At this point, from my experience, there is no reason not to buy any Apple product of any version, update the OS to the latest, and expect the usual performance and compatibility. Choose based on the hardware you like (and the new Air looks pretty fast for the money, if you’re on a budget I’d personally look at getting that over a refurb older Pro unless you’re looking at the 15" - check the specs etc. but that’s a nice system for the value and paired with a Thunderbolt 3 dock it’ll basically be as port-loaded as you like).