So excited for this one. It was the one I used for the last year on reddit.
Unfortunately this feature seem to be missing for now. The dev has an GitHub issue open on it though so it is on the roadmap.
Your instance is only blocking the weird tankie one, so you dont need to worry about multiple user accounts.
You can check federated/blocked instances here:
Prey. The first one, such a gem of a game.
Karma system.