The short answer
When sending Ethereum (ETH) from Binance to a Luno receive address, always choose the Ethereum (ETH) transfer network.
The slightly more detailed answer
Luno customer ETH receive addresses are very simple smart contracts only designed to send ETH to Luno’s internal wallets using the Ethereum blockchain.
Binance has created their own blockchains (transfer networks) for sending Ethereum, being the Binance Chain (BNB) and the Binance Smart Chain (BSC). We don't support these blockchains, which means we don't have any access to them. So if you send Ethereum to Luno using either of the two, we won’t be able to access the funds and return it to you.
When sending Ethereum from Binance to a Luno receive address, it's important to always choose the Ethereum (ETH) transfer network.