How can you remove your comment history like this?

nah

probably commented on an unlisted or private stream

Be offline for a long time

Isayisay was offline for 6 years but his comments still are there

Pochita left for a month but his comments were erased for some reason

Idk

You need to comment lots of times on a private image for this to happen

Ok

You need to comment lots of times on a private image for this to happen

How many times tho

It would take a while depending on how many comments you have, but in the comments section on your profile, you can go one by one through them all, and delete them from the image via the Delete button next to the comment.

You’ll have to ask a site mod to do that, it’s a thing they put on your account if they want your comments privated for ever privacy reasons or to avoid any harassment