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.
If it helps, for Androids share YT link to something like Untracker to remove unwanted nonsense from the url which you can then pass on safely (also works for things such as Amazon links).
For images, share to something such as Imagepipe first to remove location data. Other apps such as Aves Libre gallery or image Toolbox also strip this data but Imagepipe is simple - share image to it & it passes the image directly to your messaging app after stripping the data