I'll double down on the need for a vacuum sealer after your comments. I forgot that the enemy of just about everything is oxidation. While I have no idea how oxygen effects shrooms, I speculate that it can't be good in many cases.

But yeah, anecdotally, my mason jars have been just fine too. Each strain I have is a unique experience and does slightly change over time. While a mason jar isn't as effective as vacuum sealing for "perfect" storage, I suspect that oxidation (or just age) may alter the other psychedelic compounds found in the mushrooms a little more aggressively. (Just speculation though.)