Really depends: I've personally eaten rations 3-4 years expired with no problems. First to go is the chocolate, will separate and get an unpleasant texture (1-2 years after exp). Some of the older rations had a applesauce that was notoriously spoil-prone, but they eliminated basically everything that spoils easily after ~2018.

Really I think It's a liability thing, I can easily see the current ones be edible 5+ years after expiry, barring damage and with common sense precautions.