I’m aware it’s a thing and not really a plural. What I was trying to say is that it looks plural and since I didn’t learn about this part of English until several years into my studies as a kid, it isn’t as well established in my mind as “you are” is (that also looks like a plural, but I’m used to it).

“They are” for a single person catches my mental error filter the same way as “I are” or “you is” would, which is highly annoying.