I have been using a hidden wallet on my Trezor T and never had to use my passphrase since it was saved on the device.
Trezor prompted me to upgrade today and after the upgrade, the interface took too long to show, so it timed out. I was asked to try again or clear ‘something’ I dont remember exactly what it said. I chose the clear option.
After this, the access was reestablished but my hidden wallet was gone. My only option was to add a hidden wallet again. Now it asks me for the passphrase which I dont remember as it was ~6 months ago since I used it. Trezor never asked me for the passphrase previously as it must have been stored.
I dont remember the passphrase to add back my hidden wallet, all I have are my seeds.
What are my options? Can I revert the upgrade and regain the saved passphrase, or by any other means recoup the information?
There is no way of recovery if you lost the passphrase, and
The passphrase is not stored anywhere.
Or you know or you should back it up on paper for example.
The Trezor device does not save, store any Passphrase info, that is why it is an extra step of protection
Please check the links bellow
your passphrase should always be memorable as there’s no way to recover it if you forget it, and your funds stored under a passphrase will be lost if you forget it (therefore, please use it only if you completely understand how it works)
On the red underline you can see that the software allows to Remember that wallet which allows you to visualize your wallet and funds in it without having even your Trezor connect or the need to enter a passphrase.
That said…
This is only a visualization.
If you ever wanted to send funds out of this wallet you would need to connect your Trezor and enter passphrase to validate any tx any move you wanted to make.
Like I said previously read carefully the links I shared to understand.
Passphrase and hidden wallet is a rather a Passphrase protection is an advanced feature and they must be used carefully
If the passphrase is lost, it can only be found by guessing (brute-forcing) which is often technologically and economically infeasible.
The difficulty of guessing the passphrase varies depending on the strength (complexity) of the passphrase.