that sounds to me like an issue with interference (i.e. the switch communicating over wifi is creating signals that interfere with the controllers signal). Is it happening in other games (particularly offline games)? You might see improvements if you play on ethernet (if you are not already) & airplane mode and/or by plugging in the controller (if it is a pro controller). Also reducing the number of devices that are connected to bluetooth/wifi around it can help. There is a bunch of things ppl suggested when chara had issues in this thread:
https://x.com/ProChara/status/1698425530851459192?s=20 and this
https://x.com/ProChara/status/1699638476491149672?s=20
I am having a similar issue with my controller, where it will randomly start pulling left. I narrowed it down a bit and am able to recreate it in the calibrate control sticks menu. It only starts drifting when I move the right joystick to the Upper Right section at a partial tilt from center. So every time that i would move slowly or look around from on an inked wall as soon as I went to kid mode it would pull left.
You can see on Chara's video that as soon as he moves his joystick right slowly it starts to pull left (13-14 sec mark). It might be that he is already fighting it in the moment before it flicks left. But once it starts it can get pretty aggressive.
I have taken apart my controller and cleaned it up as much as i could. Removing any dust or hair in the controller and joysticks with tweezers or with an electric air duster and the issue remains just as bad. I am noticing that while plugged in the pull left is less extreme but still doesnt sit center.
Ive been considering modding it to hall effect but there hasnt been a compatible,consistent, or reliable joystick replacement. I was following another forum that was attempting this with some hall effect joystick on alibaba but each one wasnt compatible. The next option was to replace it with the ifixit pro controller joystick replacement. Which would be the cheaper option, but even though I am able to it might be more worth buying a new controller since the comments i have seen after the repair havent been inspiring.
I also have gulikit kk2 pro that ive been using meanwhile but its not quite the same and am constantly worried its not 100% with gyro and button presses. The A button squeaks when i try swim up walls quickly, so annoying lol. if anybody has insight on that, it would be great.