I’ll never forget my SSA letter last year. We had heavy rain the week before and the day it arrived. The letter got wet in the mailbox. The barcode got smudged.
So I called SS to report it. The agent assured me it was OK, just fill it in, include a note about the bar code smudge. So I sent it back.
Three month later, I got a “last chance letter”, since I failed to return the first one.
Always check your bar code for smudges.