ummm.........
i think i found out what happened to equibooru.
read through the comments under the image from this archived page.
it would appear that the mods or possibly one in particular , moderated the site
poorly , and disregarded requests to remove stolen content regularly
and drew the ire and, it would appear , the wrath of one particular zoo
who was a proficient hacker.
seems it was an unfortunate case of fuck around and find out.
apparently it is true, the more you fuck around , the more you find out.
sadly we all lose out because of one dipshits bad choices
it would be my assessment, that it is most unlikely that equibooru will ever come back online
*yes i know this is a page that was archived a few years ago but i saw a couple that were from last year that implied similar intent but in a much more veiled manner than the overtly blunt way it is stated on this page, but this shows that this was a significant point of contention for several years and it finally pushed someone to the point where they decided to implement the nuclear opinion and nuked equibooru out of existence