Relevant post for this thread: www.elitefourum.com/t/so-desiccant-packs-are-not-enough-to-stop-moisture-damage/23549/1
I recently drove quite far for a local deal regarding a few Shadowless cards. Upon inspecting the cards before purchase, they appeared to not be entirely “straight”. It’s hard to describe, but it wasn’t the typical curve/bend you see regularly on WOTC holos, but rather a wavey look. The card went up, then down again, then up again. It wasn’t quite as bad as the card in the thread linked above, but it was enough for me to pass up on the cards.
The dude was using one of those black airproof cases. After looking into the topic a bit more I found the thread I linked, that’s the main reason I can imagine why his cards had this.
Not trying to make you panic, but just wanted to share this since there’s more that comes to it, it seems. I don’t have a lot of storage experience myself, but it clearly doesn’t come down to “throw in a safe and forget about them for years and they will be fine”.