It seems like a recent system update in openSUSE Tumbleweed has caused the built-in Qt web view to not like working with the default seccomp filter in Anki.
No doubt this is some kind of upstream library bug, but give that it renders Anki completely unusable (pretty much every screen is blank and doesn’t render at all) maybe it would be a good idea to disable the seccomp filter sandbox within Anki if starting on Linux? It technically will reduce the security hardening of the built-in web viewer but finding out that you had to set
QTWEBENGINE_CHROMIUM_FLAGS="--disable-seccomp-filter-sandbox" in order to work around this problem was a bit tricky, and it means that I cannot start Anki from my normal launcher (instead I have to launch it from the terminal each time). However the fact that there were other Anki bugs with similar symptoms seems to suggest to me it wouldn’t be a bad idea to make this a bit easier to work around when it happens.