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> and asks me to set a passphrase for Trezor
No, it’s asking you to _enter_ passphrase for Trezor.
You didn’t set one, so you leave the field empty and click continue.
> If I choose “Toggle passphrase off”
Don’t do this. (but if you do, nothing bad happens either. but Suite might ask you to enable it again later.)
> it asks me if I want to send 0.00004182 BTC including 0.00004182 BTC fee. Is that correct ? Because I want to do a consolidation
Yes, this is correct.
You are sending money to yourself. The destination address is your wallet, so it counts as “change address”, so you don’t need to confirm it. The sum total of money _leaving_ your wallet is exactly the fee amount, because everything else is going straight back to your wallet.
It is somewhat confusing, but at the moment it’s the expected result.