Missing panel at start - plasmashell errors

I guess that makes it system-wide rather than user-config.
But it doesnt rule out bad software installation or similar.

PS.
This line is probably better than your current ‘workaround’

kquitapp5 plasmashell && kstart5 plasmashell </dev/null &>/dev/null &

And you might have a look here (for inxi and such)