it's still BTC despite the network being different. Altcoins are those that aren't BTC such as ETH, XRP, USDT, etc. BTC, on the other hand, still is a BTC regardless of the network it will be received/sent to.
I don't want to derail the thread but for your info, any wrapped token can never be BTC regardless of their value or whatever. Bitcoin on other chain like Ethereum or other is just another altcoin.