Since switching to the Fold 3, whenever I get a text message using the default Messages app, when someone texts me, it always has Subject:No Subject before the actual message. The message is sent in a separate message at the same time. It's annoying. I've tried looking in settings and there is nothing that mentions Subject.
to the OP.
I am guessing this is carrier issue. have you reached out to your carrier yet?
If they aren't able to help, then submit error report to Samsung Members after issue is seen again.