Not a therapist, though I am a counseling student. Are you replacing the screen time with anything? It’s one thing to expect him to reduce it, but if he doesn’t have something else to do in that time it makes sense he would turn back to the screens. Maybe invite him out on a hike (if you guys are able to!), or out on a walk, or to play a game.

Otherwise, I think he would need counseling for a professional to determine what’s really going on. I feel personally doubtful that he’s truly addicted to anything. However, there is likely a reason he finds life online easier than real life. I think most kids do these days! Their brains don’t have impulse control like a developed brain does, and social media is designed to keep the brain hooked.