Liverpool are still empty-handed...
FA Cup : eliminated very early
EFL Cup : eliminated in the finale
Champions League: eliminated during last 16
Now there is only the Premier League left to win. We can already call them as the champions here though. Because the gap is 12 points with Arsenal so I don't think even Arteta believes in their chance anymore.

Do you call Arne Slot successful for this year? I think winning a Premier League trophy is a good start at least. He is about to end Liverpool's thirst for this title -
the last one achieved was in the 2019-20 season.
They are repeating same fall in last months of season like the past one with Klopp. In this season, they are more lucky with sudden crisis of Manchester City and lack of severe challenge from Arsenal, so it's likely Liverpool will still win Premier League title. They deserve to win Premier League title as they are the best club in this season, but how they lost and left Champions League and EFL Cup need to be assesed internally, and they have to learn many things from those defeats, to prepare for a next better season.
Slot is still very deserved with applause with many great jobs he has done for Liverpool in his first season at Anfield stadium and in Premier League.