So I decided to play KF after a few months, and first time playing it since I actually learned about this website. To make a long story short, something seems to be "wrong" with the sensitivity calculation or KF is just weird.
For some reason (sanity check mostly ¯\_(ツ)_/¯ ) I decided to check if my sensitivity in-game was actually correct using Sensitivity Matcher, to my surprise, it is somewhat off. For the record, I made sure to disable acceleration and set my desired fov both in-game (made sure to actually set it using the console) and in the calculator, and I also made sure to double check I didn't mess-up somewhere. I also think Sensitivity Matcher is not to be blamed considering every game I've tested (a few CODs, KF2, NMRIH, Apex, BFV) makes a full 360 rotation just fine when I check.