When I switched tilesets to other tilesets like Ultica, Retrodays, etc this issue was not present.
Now, UndeadPeople also had 3 versions packed in with it. One is MSX_Undeadpeople, New UndeadPeople, and legacy. I had this on MSX_UndeadPeople. Switching to New UndeadPeople solved this. Really confusing at first what is for what without digging.
But, looking on the creator’s github, he does have a new version out. So that wouldn’t hurt either.