5
Does PuTTY detect login queries and mark them like this?
It doesn't need to detect anything; PuTTY itself generates these particular queries. As of version 0.71, it will show an indicator that marks locally generated lines to avoid confusion with text sent by the (possibly malicious) server.
See also PuTTY FAQ Why do small PuTTY icons appear next to the login prompts?
– Martin Prikryl – 2019-05-10T09:33:27.547