So to start with the “also”… vigilantism is mob justice. It is always a bad thing because it denies people their due process.

It is very, very rare for vigilantes to get it right, or to have excellent target selection. The vast majority of vigilantes go after innocent people whose sole crime is to be different- because they’re bigots.

That said, assuming you didn’t otherwise break the law (so no breaking and entry, or hacking etc) it would most closely be investigative journalism. Sure it might get taken down on whatever platform, etc, but that doesn’t make it vigilantism