Hello MetaMask developers,
first of all - I wanted to create an issue in your Github repo (https://github.com/MetaMask/metamask-extension) but the closest option was to report a bug and this is not a bug. 
So I hope it’s okay to post it here.
I’m a firmware developer at Trezor and we are in let’s say the last stage of developing a potentially breaking change for you. Release date hasn’t been set yet, but it could be sometime in January.
So far all the Eth definitions (networks and tokens) were hardcoded into our firmware binaries and this is going to change. Only few of them are going to stay there. Therefore operations on most of the networks and tokens (which won’t be built-in in our firmware) will stop working without changes on your side.
You have to update to the latest version (v9) of trezor connect (https://github.com/trezor/trezor-suite/blob/develop/docs/packages/connect/index.md) which will implement the changes for you transparently. Connect will download the definitions as needed from our servers and use them in communication with Trezor device. We are also thinking about creating a “connect plugin” which would allow the users of connect to feed it with the definitions manually.
Some technical details about changes in firmware are available here (still WIP, so there could be changes):
- definitions documentation
https://github.com/trezor/trezor-firmware/blob/marnova/ethereum_defs_from_host/docs/common/ethereum-definitions.md - definitions binary format
https://github.com/trezor/trezor-firmware/blob/marnova/ethereum_defs_from_host/docs/common/communication/ethereum-definitions-binary-format.md
Our motivation to do this change is mainly to save some memory on the device.
Let me know if you have any further questions.
Martin
