They're artifacts from a more naive time on the internet. Meta has announced that they're going away next year on Feb. 10.

Microsoft Edge has quietly rolled out a redesign for its right-click context menu, which finally fixes the clutter that users ...

So are external comment buttons, according to Meta. They’ll be discontinued on  February 10th, 2026, and starting on that date, they’ll render instead as a 0 x 0 pixel to prevent causing errors. [Link ...