As
@Ghostse said, if you have to make it an explicit rule, it's already too late.
To date, I've been the biggest political sperg at the table, and even then it really only came up twice. Both in modern games. One an Indiana Jones type adventure where nazis and commies were racing against the PCs for some treasure. The other time was when I used Klaus Schwab as the image and template for my Bond villain, back when the WEF was just a thing terminally online political spergs talked about. I couldn't pull that off now, I think people would catch on.
I did have a player leave my Eberron campaign because he thought I was MAGA (despite me being British). I assume it was things said outside the game since I was mostly stringing together heavily revised one shot modules.