Circle Pad dead zone

[MizaGBF]

One of my 3DS experiences seemingly weird inputs on the left circle pad when I don't touch it, akin to a stick drifting issue.
I assume its age is showing (unless it's a factory defect) but it only happens with this particular port, not in any other games. Of course, I also tried recalibrating, without any changes.
I'm not really familiar with 3DS development but would a dead zone applied to the circle pad coordinates in controller_3ds.c fix this issue, if I'm not reading it wrongly ?

[adlermf]

I am experiencing the same with my New 2DS XL, but mine is a slightly downward drift. It might be a manufacturing defect but it doesn't happen in any other game I played, or even in homebrew menus. I tried increasing the deadzone range in game_init.c but that doesn't seem to do anything on the 3DS.