Most of my problems seem to revolve around using an eGPU with the laptop shut. I'll randomly get intermittent freezes where the display stops updating and user input stops being accepted. When I look at the logs, AMDRadeonAccelerator is going nuts.
The AirPlay icon in the menu bar also flashes between Sidecar, Airplay, and nothing at all. I had to remove it for my sanity. Speaking of Sidecar... performance is abysmal. Not on Sidecar itself, which is actually really snappy, but it brings everything else to its knees. Probably because windowserver goes nuts with CPU usage...
My monitor isn't correctly detected when using an eGPU, but it works fine with Thunderbolt. I had to create a custom EDID with known good values for it to work properly. Luckily this was something I could fix on my own.
Oh, and every few weeks Finder will just give up and die, which has the interesting effect of preventing the Feedback application from gathering logs. Nothing will compel it to come back to life and rebooting just sits there. The only way out is to hold down the power button. This one might be SMB related, as I have a lot of shares going on and Finder might not like something that is happening with them at any given time. I've never quite isolated what's going on.
I also get T2 crashes every few weeks. They must be making progress, though, because it seems like every update the crashes get further and further apart.
Other than that... it's the same old macOS as before for me.