I still have to experience it myself, but that's what I heard and another Person I asked just yesterday again wasn't sure himself.
I'm still new to Itch.io but some stray comments I don't remember clearly anymore, talked about having to pay twice either by mistake or another time when the price got raised.
Soooo I have no example for myself yet, just something others seem to have experienced.
The product itself is supposed to be something somewhat big? I had at least read the storepage today once. I mean completely.