Spoke with the development team, this is still being worked on. There should be an update to MetaMask that adds support for EIP712 compliance on Trezor devices. We don’t have a specific release date for that update, but they’re actively working on it.
Thought it had been fixed already from the update on their end, but I was wrong. We still have some work to do from our end.
That Github link is where developers can discuss the change, and share their work.
Unfortunately, the answer for now is: wait for the update to add support.