Recently, the upgraded Tangem app added the passphrase support for their latest (version 2) cards that have the option to generate (or import) BIP39 SEED phrases. Thus, i have reset my cards to factory settings ( the procedure on how to do this can be found
here) and added passphrase to my SEED. Without resetting it is not possible to do this.
But that newly added passphrase isn't going to add any extra security to the coins on your initial non-passphrase enabled wallet/addresses. Are you going to move your coins to new addresses on your Tangem that take advantage of the passphrase feature or will you leave them where they are and add extra security to addresses funded in the future?
Right, no extra security and it requires device resetting. Probably they added it because some users love to have such feature. I kinda like it .
My stash was no affected by reset as it is on Passport 2. Tangem is used by me solely for on the go payments, largely in USDT.