Eh. The 12900k still has the edge in most single threaded benchmarks, and the latest Threadripper Pro will easily crush it on multithreaded loads (all while drawing close to an order of magnitude more power). Also your MacBook Air will thermal throttle if under load for too long, while a desktop computer offers a lot more options for cooling. Further more a desktop computer gives you the option to use faster storage and more and faster RAM which might be very relevant in some scenarios. Plus there is the whole GPU/CUDA side of things which may or may not be relevant to you.

All that being said, I'm typing this on an M1 MBP and the perceived day to day performance is better than any desktop computer I've owned, even if it will no doubt lose out a 'real' workstation when it comes to running 24 hour CFD simulations.