Sure, I hope it can be useful.
After the suggestion to create a new user I found a similar case ([SOLVED] KDE/Plasma 5 stuck on splashscreen / Applications & Desktop Environments / Arch Linux Forums) where it was suggested to delete the ~/.local/share/kscreen folder.
Unfortunately for me it didn’t work but after renaming the “share” folder I noticed that plasma was starting up, so I slowly narrowed down the field by renaming the folders inside “share” one by one… until I found that the problematic folder was " mime".
Looking at the package list in the update I noticed that there is the package “shared-mime-info-2.4-1”… I wonder if it is it that corrupts the “mime” folder for me through the post installation hook" Update the MIME type database"? I don’t know, but I’m happy that with your help I solved it, thanks again!
EDIT: maybe maybe: