Why does my left thumbstick "float" during calibration?

I received my Steam Deck in July and recently ran into an issue with the left thumbstick. I noticed that my left stick would float left while neutral, unless I deliberately re-centered it. It came to the point where it would happen unless I made the deadzone huge, which doesn't work for me (chronic hand pain). I did a ton of searching, which mostly indicated that "Joy-Con drift" is "impossible" with current firmware/software, but I'm fully up-to-date.

I tried calibrating it manually in desktop mode, but I get a "Permission Denied" error when I try to run thumbstick_cal in /usr/bin. My last ditch effort was to run it by copying it to the desktop and attempting some other Konsole techniques I found online, but I'm not confident those calibrations worked. Regardless, I couldn't get the stick to stop floating around after minimal use.

I purchased the left thumbstick replacement from iFixit and successfully installed it. I checked the calibration for it, and while it's better than the last thumbstick, it's still falling a bit out of center after movement like the previous one. I doubled-checked the right thumbstick, and it's perfectly centered when neutral every time.

Since it's still floating and needing to be recentered, could it be another hardware problem? I'm considering contacting Valve, but I wanted to know if someone had insight on either, A. if this is a known issue that can be repaired without hardware, or B. how I can verify I'm recalibrating the thumbstick correctly despite the "Permission Denied" error.

Thanks for reading! If I need to provide a recording to show the behavior, let me know.