hey just in case someone has the same issue, I thought I was running out of time for the block puzzle but I was just accidentally walking in to the exit I think. If you need help actually solving it I walked to the lower left corner and looked up a guide on how to solve a 15 slide puzzle more efficiently (basically solve it line by line and save the line with the open space for last).

I somehow did it randomly by mistake lmao

Don't know to edit my past comment but I should clarify that "the other guide" I mentioned is "Memento Locations & Secrets" By PrettyTerrible here in the steam community hub. Specifically, Chapter 8, #22. paper chain seems to indicate that the other block puzzle is solvable. https://steamproxy.net/sharedfiles/filedetails/?id=1890624484#3253331

Ha ha, yeah. As noted in the title of the painting "Disparity", the initial arrangement of pieces has the wrong parity, and is therefore impossible to solve. You can read more about this on wikipedia: https://en.wikipedia.org/wiki/15_puzzle#Solvability

Though, interestingly, according to the other guide you can solve the other sliding block puzzle in the art gallery, the "This is in fact the exit" one. It reveals a memento of a paper chain to you when you do.