AFAIK contents aren’t shared automatically between servers. See https://join-lemmy.org/docs/administration/federation_getting_started.html

Thanks for the reply. This thread may give us some clues: https://bugzilla.mozilla.org/show_bug.cgi?id=1941820

Some fonts may require additional configuration to display properly, so usually manual installation should be avoided.

Please run (and post the result here) fc-match sans and fc-match serif to check fontconfig picks wrong italic font. If that’s the case, try to remove the TTF files you’ve installed via the font manager you’re using, then install the fonts via the package manager - it should configures fonts properly.