If you sent BCH to a BTC address (or vice versa) by mistake, this is considered as a cross-chain deposit. A cross-chain deposit occurs when tokens are sent from one cryptocurrency blockchain to another.
Wallets for one blockchain token cannot support tokens from another blockchain. This means that sending Bitcoin Cash to a Bitcoin wallet would result in the loss of the Bitcoin Cash (vice-versa).
Please refer to our cross-chain deposit recovery policy for more information.