Bunk bed racking

Hardware stores sell steel braces for that purpose. They can be small or large and they are often in different colors. But you certainly can paint to match.

I had this issue with my daughter bed in her dorm. I am assuming the the bed are stack on top of each other? What I did was use two ratcheting straps. Each one going from the top of one bed to the bottom of the opposite end of the lower bed. the result was a X on the long side of the bed where is was against the wall. That helped a lot but was not that pretty. Could do something similar with steel cables and turnbuckles.

If the setup was acceptable at some point, I would consider taking the bed apart and fixing it the right way. I didn't have that option since these were dorm beds.