I think I may have a similar problem, though not as bad as the reporter's.
After upgrading to fedora 29 from fedora 28, I found a few gnome applications
are not working correctly. The symptom is that some text/graphics are missing
(not shown).

I first noticed it when the gnome weather extension's configure panel is not
showing the location list (I have two) - but selecting either of the two
entries work, so it is just text not showing.

The other application not working is a custom c# based wrapper around
webkit2gtk4. Some sites are not rendering at all: bugzilla.redhat works, but
google.com does not (nothing shows, but you can mouse over various places, and
actually type some text blindly to get a search - and some search result
quickly flashes by before it goes back to blank again- you can nonetheless
click on some links, and your mouse over shows it is on various things)