I can confirm this, this also applies to older macs that are less powerful than yours.
I initially started one of my old projects and after a long work everything started to slow down. And then I started deleting the most suspicious third party plugins and bingo, Roland Cloud was a party breaker. They leak after some time on Big Sur, I tried with different settings, first default settings, then my custom then most CPU friendly. Same result.
The second round, was with a lot audio and automations and only builtin plugins. And surprise, Cubase flaying no leaks or whatever.
The third round, I added a couple of Native Instruments to the previous project because I have never had any major problems with them and they work fairly stably. And everything works flawlessly, and I left the project to work in the loop for a few hours to be sure and we have same memory and CPU utilisation.
This is great for zero version for both sides and big macOS changes.
Another positive side, that I like a lot more builtin plugins than similar ones on the market, so I don’t have much need for other plugins,
which is invaluable for overall stability and performance.
At first I was scared that I would have to stay on the Mojave or Catalina which is not too much of a problem but this combo is my favourite so far.
I’m still testing and I’ll report here if there are major problems, but as I see it, they can be caused by older third party plugins with buggy and deprecated OpenGL api or who knows
I know I know, it’s time for a new mac but I like to see it work in impossible conditions first