If you are blocked, Instagram prevents you from mentioning or tagging the other party's username. You can check to see if you are blocked by mentioning or tagging them in your posts.

You also cannot follow or message @WilliamShatner." Prior to that, X simply displayed a "You're blocked" message while showing no tweets, replies or other content.

To double-check if you’ve been blocked, open Instagram in a web browser and search for the person's username. If their profile appears on the browser but not in the app, it could be an issue ...