The public version of the warning was that the target was a concert in Moscow. That’s pretty specific and certainly actionable. The official communication was almost certainly more detailed, but even if it wasn’t, it was enough to be helpful. Reports (and video from security cameras) indicate there was absolutely zero security at the concert, despite warnings.
There ya go with the truth again! Too bad it will be ridiculed and laughed off here.
Just 3 days ago, Putin called warnings of terror attacks "Western blackmail".