What happens to requests during switch over (transition)?

Lets say there are two servers in a proxy and both of them are declared back up and sticky table is set up on both the server.So the requests to HAProxy will be redirected to always the same server as long as it is UP.
Currently both servers are up and requests are going only to back up server A.
Lets Bring server A down,Lets say we have “server A check inter 10s rise 3 fall 3” in the configuration which means for server A to declare DOWN there will 3 checks every 10s that brings to a total time gap of 30s.

My question is what will happen to the requests that come to HAProxy during this 30s time frame? Will the request goto server A and fail or will be redirected to server B?

It will go to server A and fail. The client will see a 50x error in this case.