Hey there, when setting up the older wallet you would have been prompted to set up an address using either a 12 or 24 word phrase or a hardware wallet, in which case your secret phrase is the same as was revealed when you set up your hardware device.
There are a couple options for folks that were using a different kind of hardware wallet with earlier versions of the wallet:
[Recommended, Low Risk] Purchase a Ledger (Nano S or X) device and restore it using the same seed phrase as on your Trezor or Ledger. Then install the Stacks app from the Ledger Live app.
[High Risk]: It is also possible to recover your funds by using a software wallet. Be warned: it is not a recommended security practice to enter your hardware wallet seed phrases to a software wallet. Only use this method if you have removed all other funds from your hardware device first.
Note that if you choose to do nothing, your Stacks will remain safe. You won’t be able to send your Stacks until you upgrade to the new version of the wallet and recover your wallet from seed phrase OR transfer to Ledger.
I hope this helps - let us know and happy to answer any other questions!