[OTHER/BUG] Space width broken on websites with font-family set to a system font, tables broken. (Kubuntu 25.10)

[9vlc]

Please explain your inquiry.

Websites like Wikipedia and old-dos, where font-family is set to a system font alias that is not monospace seem to have lots of formatting issues like font spacing and no tables.

Old-dos opened in phoenix:

Old-dos opened in stock firefox:

Wikipedia in phoenix:

I'm using the firefox deb package from Mozilla repositories: https://support.mozilla.org/en-US/kb/install-firefox-linux
Snap package first removed like this:

snap remove firefox
snap disable firefox

Kubuntu 25.10