I keep seeing people talk about how the masterpiece my take place in a different timeline, could you explain it to me? Because from what I know it was just the LE timeloop, it even had john getting retcon powers within the loop

Yeah, but there’s more than one version of John able to do the Retcon stuff too, remember? Thing is, Caliborn sees himself Surprised in the Masterpiece, even though he’s just literally seeing himself get ambushed, and the fact he has the Ring of Void is extremely strange as well. There are a few things that could imply another Timeline. Or maybe not. It’s just a little thing to think about.