I believe it's mentioned it in Dev Notes section of OPBig thanks to Nefastus for updating the game. I'm curious if anyone can tell me what happened with this latest update to cause the file size to go down? I was considering the compressed version with the last update, but now I see no need.
In the changelog, the pevious update introduced compression in the new scenes, but the latest update mentions nothing of the entire game being converted to webp and I'd imagine that would be quite notable.