I did have this issue earlier in the year with the FF7 release, PISSED ME OFF!!!!!! :D
Especially considering FF7 was a D-pad game, not an analog game, but they set run controls to ONLY work on analog - which is silly considering the FF7 only has 8 directional movement; super awkward with analog sticks.

The way to fix it is simple and non-invasive (no unscrewing and risky crap like what needed to be done on N64 controllers that had loose analog sticks).

THE FIX

What you need: cotton swabs and cleaning alcohol. This stuff is dirt cheap and available all over the place.

1. Look at the analog stick and notice that there is a bit of rubber covering the top of the ball.
2. Take a swab, dip it in the alcohol, and use it to push back the rubber covering, and circle around the analog stick about 15-25 times, being thorough. 3. Load up a game and see if it is still occurring, if it is, even a bit, repeat step 2.

It's been months now, and I haven't had issues since.
It probably helps my kids have their own Switches now.

Not had this with any JC but with pro-controllers apparently it's due to a build up of dust that seems to mainly happen with the left stick what backs this claim is that if you hold the stick in any direction while pressing it and blow into the edges it seems to sort the issue out on the pro-controllers.

After reading your earlier post I tried this. The joycon is still drifting but it's way less noticeable and its useable now. Hopefully it says like this.

Joy con flips out in the menus, moving down on their own. in games the camera moves wildly, so its either joycon drift or the controllers need an exorcism.

Hopefully you also tried recalibrating after the fix.  If it helped a bit you might try the same cleaning method again and see if it fixes it completely. Also, maybe share your results in the OP so new people coming in to the thread can try this pretty easy fix.  It was a life saver to me, that's for sure.

Hmm...maybe I will not buy a switch now. Can you imagine if this happened to Sony or Microsoft??

RROD and Faulty Game Damaging Disk Drives helped the 360 and PS2 numbers respectively.  When people love a product, or a woman, or a movie, or whatever, they accept faults and limitations because their love overrides these obvious negatives.  Every console has had its share of pros and cons...and in this case at least we can just use a Pro Controller rather than purchase a brand new system 3 or 4 times.

I have 10 joycons and 1 lefty has just started drifting up. Not terrible yet but still annoying AF.

man oh man, you’re always so feisty.

no problems at all with my pro controller. Wasnt’t aware there were any. Thanks for the well meaning information.

I got this with 3 of my xbox controllers within 1 month (i'm now using a cheap ass 3rd party wired one and it works great and was half the price). Only once with my Dual shock.  But yeah my nieces have drift on their switch.