Looks like the 50 grand "remodeling" job the previous owners had done to "finish" the lower level of my house back in the '80s.
In my case there were no nails, screws, or even evidence of a crimper used on any of the corner bead anywhere.
They also did cute stuff like leaving taped-up live wires wrapped around a water pipe.
Many trips to the dump later, there's no evidence these monkeys were ever here.
Your problem is more easily remedied (I hope) by just screwing in all the bead and refinishing the corners.