I was a big fan of Tiled Menu (a bit like Windows 10) in neonuser, but after update to 6 it does not work because it was written for Plasma 5.x. I have seen a post about this elsewhere and someone responded about changing some values to make it work in Plasma 6 but no guidance on how/where to do this. Any guidance greatly appreciated.
Plasmoids (Plasma Widgets) from Plasma 5 needs to be prtted to Plasma 6 - many things have changed and backwards compatibility doesn’t actually work.
Develop KDE has an article about it: Porting Plasmoids to KF6.
I used this article to port one widget and it requires some work but definitely doable.