Many people don’t realize the disabled military qualify for Social Security Disability as well as Veteran’s benefits. So some of the new claims are from military.
Another issue, hubby has a friend that has been working with serious back issues for several years. He kept seeking treatment, toughing up and working. Finally he became unable to do the job he was doing, running heavy construction equipment. If jobs were plentiful he may have found another job he could do and been able to keep working but is now on disability. I have no idea how many that are now getting on disability have been working in spite of their disability but it may account for some of the new claims.
Sooner or later the system will collapse. In the meantime Democrats will lock in their voter base by making them dependent on the benefits.