I have the same issue, camera stutter. BUT ONLY ON ONE OF MY PCs. See below.

PC 1 specs - no stutter
https://imgur.com/a/kks7f

PC 2 specs - stutter
https://imgur.com/6tK9bKN

They both have the same gaming mouse so the polling rate is not the problem (yes i still tested it). I also tried turning off steam cloud on PC 2. Didn't make a difference.

Differences between both PCs:

PC 2 has a dedicated sound card, PC 1 is onboard.

PC 2 has a razer mechanical keyboard, PC 1 has G.SKILL mechanical keyboard. I unplugged they keyboard and shut down the razer synapse, it didn't make a difference.

PC 2 has a 1440p 144hz monitor. PC 1 has a 1080p 144hz monitor.

Next step is going to be to compare background apps between the systems.

Any ideas are appreciated.