Make this move to deny access to part of a site. It could be something that's been there all along, like a locked door or a chasm. Or you could cut the PCs off as they explore, via a cave-in, a trap, a bridge collapsing behind them, etc.
Maybe there's a key they can find, or a way through with a lot of effort, or another, riskier path?
Or not. Sometimes the way is shut, and they have to turn back for now.
"No, the slab is solid, and probably a foot or two thick? It's weird, though. This very much feels like an entrance. The way it's inset into the construction around it… did this, like, fall into place? Regardless, you don't see any way to lift it up again. What do you do?"
"What's the best way through? Well, not that way. The passage is just gone, like rubble and rock and dust floating in the air. If you want to rejoin the others, you'll need to loop around, back through the shrine and the central chamber. What do you do?"