I guess so.
So I just realized how this all makes sense.
That file is provided by one of these packages:
beelink-kde-settings
minisforum-kde-settings
slimbook-titan-settings
And all those packages are in a broken state, requiring and depending on plasma5 themes.
How you updated at all while keeping those does confuse me a bit.
( maybe your earlier update attempt used pamac or yay so it grabbed the plasma5 stuff from the AUR, then you used mapare and installed needed packages and updated? )
I also suggest checking your foreign packages.
pacman -Qm