Trying to install multimedia coders breaks Plasma 6 on Fedora 40 for me

Second time doing this with same results. Admittedly I followed a guide I used for Fedora 39 / Plasma 5 which worked fine but perhaps uses packages which don't play nicely with the latest versions. I also didn't use the RPM Fusion repo which apparently is a bit more ahead of the curve.

I installed / upgraded the following: $ sudo dnf install gstreamer1-plugins-{bad-,good-,base} gstreamer1-plugin-openh264 gstreamer1-libav --exclude=gstreamer1-plugins-bad-free-devel

I still wasn't able to play videos afterwards so rebooted and now Plasma is toast. It takes much longer to load up and, when it does, it can no longer load Folder View, Application Launcher, Icons-only Task Manager, or almost anything else. They present errors along the lines of: Cannot load library /user/lib64/qt6/qml/org/KDE/...

The first time this happened, I had configured quite a lot of things during that session so didn't know whether to chalk it up to the multimedia stuff but, now second time trying after a clean install, I've isolated it to that.

You might have gathered from my post that I'm no expert and I'm not even sure how to get to a terminal in this state to check anything. My suspicion is some differing qt version when installing the multimedia stuff but I don't really know.

Has anyone else had this? More importantly, does anyone know how to fix it / a proper way to install multimedia coders for video / audio?

Thanks!

**Edit if it matters... Wrote this on my phone and it auto corrected codecs to coders.