When you share a YouTube video using the share button it adds “si=some_unique_code” to the URL. If you don’t remove that it shows your personal account to anyone who receives it so that they can chat directly with you. For a lot of people this is their real name.
I’ve seen it all over Lemmy so I figured I’d mention it here! You only need the stuff before the question mark in the URL to let others see the video.
This can also be turned off in your YouTube settings under the privacy section. The setting is “channel visibility for shared links”. It will still add the si code for tracking though.
It doesn’t do it in comments, just when you make a post.
IMO You should add that detail to your top-level comment, as it’s going to be seen by more people than this clarification that definitely runs counter to how I interpreted your comment.
That would explain some things. Isn’t it a little bit odd to handle those differently? Oh well.