I don’t know for forex but someone has actually told me something similar about watch only wallet. They give you the wallet seed phrase and since it is setup to be a watch only wallet the imported wallet will be showing the funds on the wallet and then the scammer will instruct the victim to send in some coins mostly bnb to the wallet and that it is the only way for the send option to open up.
Similar scam was happen to one users in our telegram group and targeted person was lucky that he did not deposit big fund. We should always import wallet in other wallet also especially safepal or Trustwallet download from Playstore. sometime when you create wallet in these forex sites give you phrase but its working only in their site and there is no real asset store and you cannot have full access to this wallet. Wallet address checking is very important because sometimes when you import wallet in other wallet or same wallet you will get other address than previous and you can lose fund also here.