how to fix ERROR : Forbidden key path
always happen on testnet like starknet rinkeby or mumbai
it been like this since i update a firmware to 1.1.1.1
go to Trezor Suite, settings, Device and set safety checks to Prompt.
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alternately create a separate account for testnets in Metamask and select “testnet path” when creating it.
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this method work for me Thanks 
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I am having the same problem. Set Safety check to prompt but still the same problem. I have the latest updates and have install the Trezor Bridge???