After updating to Monterey, Firefox fonts are broken

I've just updated my mac to Monterey and after that I found out that font is just different that it used to be before the update - the tab title is quite small and fonts on websites are both different and missized:

It seems the FF option Allow pages to choose their own fonts, instead of your selections above is not working anymore as from what I understand it should load website based fonts instead of the one you select in FF settings (I have it checked obviously). I haven't try to reinstall the FF yet but maybe there is a way to fix it without doing so?

I use Macbook Air with M1 chip.

Solution 1:

As explained in https://bugzilla.mozilla.org/show_bug.cgi?id=1715898#c5 this bug currently occurs if macOS 12 has a non-english primary language set. As a workaround the primary language can be set to English in System Preferences (at least in my case no reboot was required, it was enough to restart Firefox afterwards).