Don't go around throwing the word "doxxing" without actually knowing the meaning of the word or the full context of things.
Every information about an Idol is known as "past life" in Japan. "Past life" are informations that is available and made public by the person/s (in this case are hololive talents) in the past and it is normal. Yes, it was information that is made public aka PUBLIC INFORMATION. The westerners are not familiar with the "idol" culture from Japan, therefore the westerners didn't know anything about the "past life" thingy and immediately assumes that these "past life" is illegal/bad. And starts to throw around random stupid shit such as "forbidden knowledge" or "doxxing" without knowing that these are called "past life" and it is not illegal/bad or even considered as doxxing. You can't dox or considered as doxxing someone with public information