No, I did not. After my post I got an mlt update too, which didn’t help with Kdenlive, but Inkscape stopped working… Right after that Inkscape got an update and now it works again. It all looks like an known issue they are aware off? Couldn’t find anything related in KDE and Archlinux forums a few hours back.
Last time Kdenlive broke, I used Flatpak until that was resolved. Maybe I’ll wait a bit again. But will have in mind to downgrade mlt, but I’m hesitant to downgrade libraries other tools may depend on.