This happened to me on Catalina with my old 2015 15in MBPr and now on my M1 MBP, and has been an issue on 11.1 & 11.2. I’ve reported it, and hopefully they’re actually looking at it.
it seems like, from what I can tell anyway, is that the preferences file that gets written to that stores the order/placement of your apps and folders in Launchpad is acting like it’s Read Only or just isn’t being saved. I’ve tried resetting Launchpad a few different ways and it always ends up broken.
I have an M1 MacBook Pro, I didn't face this issue in BigSur but after upgrading to Monterey. I did notice one thing though that this issue seems to happen after I installed Final Cut Pro.
Interesting thread... My 2011 MacBook Pro 13 just started doing this on High Sierra.
I seriously wonder if anyone at Apple ever uses their own product. Somebody has to have seen this in-house with the number of years it's been happening.