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It’s probably a change address, but usually Trezor doesn’t show the change address. This can either be a problem with the app, a changed security policy of a recent Trezor firmware, or some attempt to send to a hacker’s address. It would be best to make sure that this address is really your own.
To not show change address, the app must tell Trezor to use its own address, it must be one of the change addresses for the wallet that is used, all funds used in the transaction must come from this wallet, and there must be only one change address in the transaction. Also the wallet must be a standard wallet supported by the Trezor firmware. If anything is off, Trezor errs on the side of asking for confirmation for the address.