There’s an interesting set of challenges on https://protohackers.com/ , which I think are very suitable for solving in Erlang.
I would recommend someone trying to learn Erlang (or any beam language) to try those out.
From the site:
Protohackers challenges you to create servers for network protocols.
We give you the protocol spec. You write the server and host it. We automatically test it. There’s a global leaderboard for the fastest solve times and a new problem every ~2 weeks.