I found a little about the problem I thought was related to the post I linked:I think these could be related to UXP in general, as this other issue looks to be: /viewtopic.php?f=41&p=251245.
When I updated to v. 2024.05.01, there was some pages in which the numbers were not showing. Setting gfx.downloadable_fonts.enabled to false would solve the problem. If you combine gfx.downloadable_fonts.enabled = true and browser.display.use_document_fonts = 0, the numbers won’t show up (the fonts I use are size limited, i.e., bitmaps). Looks like they fallback to the Twemoji font, which doesn’t has numbers. Probably, before v. 2024.05.01, the missing font wouldn’t fallback to Twemoji, but to a more reasonable font (a system font, like Free Sans/Serif, in my case).
Considering the time when the problem started, I guess it might be related to this: https://repo.palemoon.org/MoonchildProd ... 0298f55eb6
I worked around it by adding FreeSerif as a fallback font in my user.js file.
