Puzzling really. He’s been in bad form for a while, Klopp if anything has been constantly giving him loads of encouragement, you can see him after he does something in a match being all over him with praise after the whistle, so the reaction doesn’t really add up. Like others have said surely he has expected to be dropped for a long while. Must have been something petty imo, maybe being subbed late or something, to then play shit won’t have helped.