Letting people know while maintaining plausible deniability.

So you can actually see. Since you did it worked.

A few reasons, though I do not buy mask theories personally:

A) They love to rub it in the public's face, or it's a part of a ritual of consent where they tell or show you what you're doing and then misdirect people (that's not really a mask, that's just Biden's facelift changing every other day!)

B) If it were white hats, it could be there specifically to communicate their presence or get us asking questions about it because it catches our eyes.

There are probably a few other reasons, but as I said I don't buy it personally.