There are some natural holes in the roof, this may be that or may not as all the ones I've come across were straight lines over 10 blocks long. The 1.20 update changed terrain generation slightly and caused some sort of bug.
I've found quite a few of these in freshly generated chunks.
Edit: Theres a sign in the overworld at a nearby portal from an admin about it, they're already aware.
I've found quite a few of these in freshly generated chunks.
Edit: Theres a sign in the overworld at a nearby portal from an admin about it, they're already aware.