In summation; you should have NO critical data on a thumb drive / flashdrive for permanent retention. They were never meant for long-term storage and while reconnecting them to a power source will help long-term (yes) they are only intended to help with sneakernet data transfers not permanent storage.
Hard disks are still the best solution for long-term storage since so long as the physical disk is intact. Even if the controller electronics fails the data can still be recovered. Optical disks begin losing data after only a few years, generally from the outer edges in unless the reflective coating begins to degrade, and if a flash drive or SSD dies then you have NO chance to recover any data.
Think of thumb drives as the electronic equivalent of pencil-and-paper medium as far as “longevity” is concerned.
Ahem: “Hard disks are still the best solution for long-term storage since so long as the physical disk is intact even if the controller electronics fail the data can still be recovered.”
Sorry. Been quite ill for a time and having trouble thinking cogently for long.
Okay - I carry some flight plans on them plus other useful aviation stuff that I can plug into any computer if needed.