The big problem is that this person isn't yet banned from Hexbear if they're able to see and downvote our posts. That means there is some transphobic creep out there stalking transgender users on Hexbear. We can't yet know if this person will try to sift through posts to dox trans people once they realize their downvotes have no effect.
That is a very common outcome when a transphobic freak feels their harassment isn't effective, see the entire history of KiwiFarms. And while we're on that subject, we also have no idea whether this person will organize raids on Hexbear by posting screenshots to the very many transphobic discord servers that literally only exist to mock and ridicule trans people in an attempt to pressure them into suicide.
Evil pieces of shit like this should most ideally be shot in the head. Second most ideally they should be publicly doxed and their friends/family/employer informed of their behavior. Without the means to accomplish those first two actions, the next best thing we can do to protect our trans comrades is to find out what account is doing this, and ban them to ensure they'll never be able to interact with Hexbear on that account again.
If the lemmy.ml admins are cooperative with that goal, then we can ensure the next reactionary on lemmy.ml who does this can't hide behind the anonymity of downvotes on their new, not yet banned account.
It's not "just a downvote" when it's clear they are targeting any and all posts on the comm specifically for and by trans people. It'd be absolutely ridiculous to think this is just a coincidence where they happened to find fault in literally all of those posts for reasons other than transphobia.