Freeze dried food says on the package that it’s only good for a certain amount of time. Hm. Some of the stuff I have - it’s years old - stays good for an indefinite period of time until it’s been opened. Then it will only last so long, but note that I have some that’s been opened (freeze dried spaghetti with meat sauce) for quite a while and I note no ill effects from eating it. (Although I’m not crazy about it, either. On the other hand I’m pretty sure it would taste like the best thing ever if I had not eaten anything with meat in it for a couple of months.)
Canned food: I tell Mr K (not the one on this forum) that when he’s buying soup or canned veggies/fruit that he should every other time or so by a can of something that neither of us will enthusiastically eat. These canned goods are set by for hard times. I’m still not tempted to eat them (canned peas for example: frozen ones are WAY better) so that’s a good sign.
The food is designed to keep you alive. That’s about it. Try living on C-rations for a few months. Lol. You might prefer death.