It does say it was cross-posted (to 3 places) at the top on the web.

I don’t use a respirator at all, but I also don’t hang out in that room while it’s printing, and I have a small air purifier that runs in there full time.

Ah, I didn’t realize the black sensor could do that.

Have you tried calibrating it with something covering the plate? Maybe painter’s tape? Can the plate spin 180 and calibrate there, to make sure it’s not different somehow on the right and left?

So you’ve used one of those mechanic leveling tools to manually set the screws so that the bed is the same distance from the nozzle in all 4 corners, and the automated probe is telling you that it’s 1.5mm off from left to right? That’s pretty weird.

Someone else mentioned there being flex/deflection in things, and I think that’s something I’d look at first. But I’d also look at the sensor and see if there’s a reason it would do that. Is it still the stock black or blue sensor? I never had problems with mine, but I’ve heard a lot of complaints about them, mostly that they’re not accurate, especially on certain surfaces. Since they sense metal, maybe your bed has extra metal on one side vs the other?

I’m just spitballing here because it’s weird enough that I can’t really imagine what’s going on.