Updated my laptop LR. I use a personalized identity plate: graphic on the left, modules on the right.
The font size of the module list (upper right) is now, after the 12.3 update, always 58 or more, no matter what font, no matter what size I set it to. I change the font size to 10, it looks correct in the dialog, but the size in the main windows is still huge.
De-installed (and wiped data) and reinstalled. No change in behavior. Using text on the left does respect my font size selection for it, but no change to the module list.
Does not behave this way on my desktop system.
The laptop is a Dell XPS with a 4K screen; Intel UHD Graphics 630. All drivers are up to date. It is most likely a driver problem on the laptop, but I'm bringing it up anyways.
All that said, setting the font size to 4 makes it a reasonable size. My guess is that there is a mismatch between the Windows scaling factor (250% in this case) and the information LR receives to compute the size of the diplayed text. Maybe.