Yeah, looks like the default “word_wordnumbers” usernames that reddit gives you if don’t change them.

Funny enough, this started happening on YouTube (comments) as well, around the same time.

The issue with sites starting to use numbering as part of the default username only started happening after AI posting became a thing, because an Achilles heel is the fact that AI can’t come up with enough believable unique names for all the posts they want their AI bots to make.