Creating a circle of transparency around the player on a 2D Tilemap

I'm working with a 2D Tilemap, and I want to replicate the hidden walls effect commonly seen in Mario games

For the time being, I've managed to create a shadow of where the player is, but I'd much rather have the foreground become transparent. To be clear, I don't want to make the entire foreground transparent, only what's near the player.

I've looked around and haven't really found anything that could work. Can I target specific tiles in my tilemap? Or do I need to use some shader effect?