Hardware devices, such as a Trezor or Ledger, periodically release firmware upgrades for their devices.
If you have not yet initialized your hardware device and added it to Casa App, and you don't have funds on it, you are safe to upgrade your firmware.
Once you've initialized your hardware device and added it to Casa App as part of your multisig setup, we recommend upgrading your firmware with caution, and never more than one device at a time.
Some firmware updates may wipe the device and require the seed phrase backup to restore. Since our recommendation is that you not keep a copy of your device's seed phrase, if your device is wiped by the update, you may need to perform a recovery transaction using your other keys to swap it in as a new key, because you will not be able to use it if it has been wiped.
It is important, though, to keep the device up-to-date so that it is compatible with third-party software like Electrum or Specter, in the event that you needed to perform Sovereign Recovery.