The issue here isn't Big Sur but the M1 chip architecture.
Big Sur is a universal binary so it will install different code on an Intel based Mac than it will on an M1 Mac.
The Waves plugs (v12) will work in Big Sur on the Intel chip set but not on the M1 chip set - yet.
The waves plugins (like a lot of other manufacturers) are having trouble with Rosetta 2 on the M1 Macs so the M1 based Macs are not translating the Intel based plugs properly which is why they don't work. Waves are working on M1 native code which makes sense. If a piece of code is not working on Rosetta 2 I suppose it makes more sense to spend the time writing native code than it does to try and tweak existing code. It might take a few months though.
From the Waves website:
CPU
Intel Core i5 / i7 / i9 / Xeon
Apple M1 (ARM-based) processors are not yet supported.
Memory
8 GB RAM
8 GB free disk space on the system drive
Operating System
10.13.6, 10.14.6, 10.15.7, 11.0.1 (Intel only).
We, unfortunately, have a triple issue here. When an OS makes a non incremental leap, you get a fair amount of breakage. When Logic makes a .0 leap (10.6.x) you get a fair amount of new bugs. When hardware architecture changes you get at least a 6 month re-coding period. Some software won't make the transition at all!!
Right now, we have all 3 of these things at once. The chip architecture isvery impressive but it's going to take a little while for 3rd party software to catch up.