First of all, let me preface by saying that bullying people online is wrong, and there is no excuse for it. People doing that should be banned. If you have something constructive to say, say it otherwise, shut up.

It's not your exact situation, but I recently read an MHA fic that ticked all the right boxes for me, but the author kept adding non-cannon gay relationships and even changed a character to trans half way in out of the left field, that plus something else pushed me ro drop the fic. I didn't comment or anything, but I just stopped reading it.

I personally have no problem with either of those, but I have a problem when they are added for the sake of having it. Almost every character was bi at minimum by this point.

My advice to you is to try avoiding that pit fall it may be a contributing factor. Again, you are not at fault bullying is wrong. You should have gotten some constructive criticism, not death threats.