• Bug encountered while playing on GeForceNow.
• Game owned on Steam, played on a PC.
• All DLC active, including TwR.
• No mods.
• I can't share any file

In my last game, I got this notification:

I already got the same on turn 137 when Tjilbruke did switch culture.

I got at least this other one a bit later (the turn right after the switch too).

And maybe a third but I'm not sure anymore.
I always got the normal ones for all cultures, including those two cases.

Good luck!