warning message: unsafe connection

I logged in to lichess but got the message: Unsafe connection, cybercriminals might want to steal your data.
First i could not log in, but i know a trick to avoid this. I set security settings to 2 way -authentication
What happened? Should I take mother measures?

Also I see the message "not secured" left of the address bar

probably on the wrong website or your security/internet isn't very strong

Are you using a custom background?