My personal levy size suddenly decreased by more than 50%… what could have happened?

I don't know what happened, but in three months, without apparently anything of note happening, my personal levy size more or less halved.

I would stress out I'm talking about personal levy, not vassals. Is there something that can affect it?

I gave out a single city to a vassal, but clearly it's not that: it was a ~400 soldiers city, and we're talking about a ~11000 to <3000 drop.

My demesne is too big, but it was so even before (actually now it's 10/6 vs. 11/6 of before). I didn't change wife, I didn't change councilors. Maybe a different heir got voted, but I can't see how that could be related either.

I converted one of my counts to my religion, but, again, what she did in her own county could hardly affect what happens in my demesne…

I'm absolutely clueless about this, I'll attach a couple of screenshot, let me know if you need more data.

Some more screenshots.

I've just noticed a very strange things: the portraits of the females changed! Including the deceased ones… is that normal?