This is a really weird one. I've never seen it in any Insiders release and I only play my custom Civ. Could it have something to do with the colors you selected for your custom civs?
No idea, I was hoping someone else could reproduce the issue.
I'm going to delete the civ(s) and recreate under 2.2.
Unless it was made under base super nova game (1.2 I think), then when I removed all the gc4 (base, SN insider and SN base), and reinstalled only SN safe/base version of 2.2.5 it was downloaded on sync with EPIC.