For context, im doing my first rig for the first character ive ever made and am very new to anything 3D.
This also happens when i move individual bones that pull the mesh away from that area (such as the spine)
Im pretty sure the vert encountering the issue is the one at the bottom of the back of the neck.
Ive done merge by distance on all vertices, checked the weight painting which im pretty sure is fine, and ive tried assigning the armature vertex group of it to the spine2 bone but that just causes it to happen to even more of the geometry (before it detached the skeleton and dragged the vert with it but for some reason that changed and it started doing this)
Any help would be greatly appreciated!