It’s not confirmation bias but rather slight functional illiteracy from commenters. The original question is basically asking what’s the connection between black superheroes and having electrical powers; or in other words why is it a trope.

Nowhere in the title or the short note did OP ask people to name black superheroes without electrical powers. He only says that he saw a video that asked people to do that.

Even if you ignore the note, the title itself isn’t asking for examples of exceptions but rather for an explanation. It’s kind of like if someone asked why so many members of Congress are old and white, and the responses were just listing non-white and/or younger representatives.