I can't say I'm surprised. A little over a year ago, they revamped the site and took away everything people liked about SJ in the first place and turned it into a shitty Tapas/Webtoon clone. When they did that, rather than stay with the shitty knockoff site, all their content creators just moved to Tapas and/or Webtoons.
I was one of the ones that jumped ship right when they made all their changes. I specifically choose SJ over Tapas or Webtoons, because I liked that SJ let me have an entire website that I could customize, and they focused more on single-page comics, rather than the vertical scrolling format. Then overnight they get rid of customizable sites, switched to vertical scrolling format, removed my ability to interact with my readers, and deleted their forums. Why on Earth would I stay after that??
A few of my regular readers suggested Tapas, I migrated here and never looked back. SJ 100% brought this on themselves.