I recently bought a 6700xt 12gb used, it is about 20% faster than a 3060 12gb in rasterisation, but uses more power (upto 220w). I paid 250€ in germany. since you didn't mention cuda, i think the 6700xt could have been even better value for you.
what part of the gpu did you monitor? i guess in video editing not all functions of ghe gpu are used equally or the effects used dont scale well on gpu.
The windows client has denuvo anti-tamper.
Linux client doesnt have denuvo and is already cracked.
I dont think civ 7 has anti cheat at all...
Just google "civ 7 anti-cheat", I have not found a single source for any anti-cheat. They only talk about denuvo anti-tamper.