From what I heard your rating can become static. Basically P/T after you turn 55. But if your younger than that then if your not P/T they can re evaluate you and possibly lower your rating.
I may be wrong but I thought that’s what I read.
Edit: Just looked it up.
- The VA may grant a permanent rating if the veteran's condition has persisted without improvement for at least five years.
- The VA may grant a permanent rating if the veteran is over 55 years old.
So if you had a rating consistent for 5 years they may give you permanent rating. Have you looked into the benefits letter recently