OK, so it sounds like you may have a loose ribbon cable. I have had a couple of similar issues where the number of lines is not reporting correctly so the system doubles up or halves weirdly. This has in most cases been a loose or dirty ribbon cable connecting the screen to the motherboard. Unplugging and replugging the ribbon cable is likely to solve the issue if that is the cause, you really don't need much friction and ribbon cables are very delicate.
I think the update timing is probably just a coincidence, there is not really a simple path for updating something to impact your screen in BIOS unless you have microcode updates or something similar, but really it is probably not from updates.
OK, so watches come with a few different standards for the pin length, the gap between the two metal rings that watch pins pop in to. The pine time seems to use 20mm bands, so searching for those on your internet purchase place of choice is the next step.
https://pine64.org/documentation/PineTime/Accessory/Watch_band/
The documentation links to a couple of options in the link above, but any of the bands for a galaxy watch which are 20mm will do just as well. All you need is to make sure the pins are for a 20mm watch and the rest works itself out. Good luck!