In CS GO, 16:9 and 16:10 resolutions are way smoother than any 4:3 resolution.

I saw lots of old posts about this and no one ever fixed it. I'm so done since this is happening for a few years.

GPU - RTX 3060 Ti, CPU is Ryzen 5 3600, fps capped at 400, never dipping below 300. Monitor AOC AG251FZ 240 Hz.

My thought is that this is related to the CPU, however I remember having the exact same issue with my old Ryzen 3 1200. I'm even thinking to switch to Intel to see if this is somehow related to AMD CPUs only.