.1 was hotfixes to do with the major release.
Everything since then appears to just be shipping features as soon as they are proven stable.
This requirement is designed to be hard, and as such is a major red flag to me.
What else is this company going to be difficult with?
Can i only get customer support or cancel my account in person, between 9-4 on the 2nd Friday of the month?
I would consider alternatives, if possible.
My gut suggests it’s a font issue, like librewolf is using a system font and firefox is using embedded or downloaded fonts.
backing that up with a search, I see there’s lots of people complaining of font rendering issues of various types in the librewolf subreddit: https://www.reddit.com/r/LibreWolf/search/?q=font
I don’t know what your fix is, but I hope this helps guide you.