I played a few Farmers' Markets in a row on my turn, I think it was 4 of them. One of them trashed itself so I could gain VP from it, but my play area showed all of the Farmers' Markets I had played, including the one that had been trashed. The game log and the contents of my deck appear to be correct, it's just the display of the play area.
In case it's relevant for reproducing this, I had played the Farmers' Markets all in a row so they were all stacked in the play area. Also, I believe the first one or two of them were Crowned. They were at the end of a Crown chain so the cards I was putting in my play area were consecutive Farmers' Markets.
It mattered because I was using the play area to count how many cards were in my deck, which mattered when I wanted to 3-pile on Gardens later that game.
sort of related, when I play a Ratcatcher, it doesn't stay in play. It goes off to the tavern mat like it's supposed to. However, when I call a Ratcatcher and then play some Ratcatchers right away, the play area shows a stack of Ratcatchers (it shows that they aren't moving to the Tavern mat like they should).
It seems the logic that tells the play area when to stack things in the play area is related to the card being played and not necessarily whether or not it's staying in play.
This is a visual bug only... you can verify by reloading your page when it happens.
We certainly need to fix it, but fortunately the gamestate is still ok.