Ok this is a bit of a weird problem and I can't believe I only found out today, but my sensitivity scale is messed up. Right now, I'm on 1.8 in-game, 800 DPI, and default Windows multiplier, which should be 11.36 inches/360. However, when I move that amount, I only turn approximately 270 degrees, and the in-game sensitivity that gets me to 11.36 is around 2.35.
I tried 1.8 on KovaaK's with the Source sensitivity option, then used a sens converter and tried it on Valorant, and even tried 1.8 on Open Fortress, and they all yielded around 11.36 inches/360 (literally just me with a ruler so it's imprecise but it shouldn't matter). This pretty much isolates the problem to be TF2 specific, and I have no idea what's going on. My mouse accel is off and raw input is on, and to make sure that was actually true I moved my mouse at different rates and consistently got the same wrong inches/360.
I have no idea what's going on, and any help would be greatly appreciated