Just for information sake.
I just updated a 2015 MacBook Pro to 'Big Sur', with a 27" IPS monitor connected through Thunderbolt/HDMI connector.
Using a DeathAdder Elite, which I have replug in if I restart computer. That'll be a Razer update. Works fine once I do that.
Game seems to play fine still, I do notice that the fan comes on a bit more, prolly just CPU load, I haven't looked at it, so far not a problem.
I also notice bigger chunks of memory usage and recycling, this MacBook only has 8GB hardwired, see how it goes.
Anyway, NV WGT plays fine, no lag or stuttering. Meter fine.
Good luck... ;)
As a bit of an update, I've notice that there are more 'resolving shot' lags going on. The game hasn't quit or locked up, sometimes I get the connection 'retry' thing, as soon as I click it the shot fires, every time. This is making me think it's something in the game update, buffering of some kind perhaps.
I'm still getting decent connection speeds/rates. No dropped/corrupted packets or anything weird going so I don't think it's Big Sur related. See how it goes.