What happens if you send ERC-20 to BEP20?

So, I'm curious, what exactly happens if someone were to accidentally send ERC-20 tokens to a BEP20 wallet address? I know they're both types of tokens that exist on blockchain networks, but I'm not sure how the systems would handle such a mismatch. Would the tokens simply be lost forever? Or is there some way to recover or convert them? I'm hoping you can shed some light on this for me.