I resigned before game end but got a warning message

Hi

On the following bullet game: lichess.org/4Y4oasBJ2g4n

I did resign but notice a message in the chat box "Warning letting time run out instead of resigning is bannable"

If he take, then is Q -h7#.

Sorry if I wasn't clear - I was playing black

So yeah he got me good, I resigned when I noticed this =)

You shouldn't play bullet, if you need 20 seconds to recognize a completely lost position.

Clearly a mistake of the algorithm, thank you for reporting.