The fact that Klopp decided to leave the post of coach only causes respect, because he did it himself and moreover understands perfectly well that to sit in the same place, in the same post for a long time will harm not only him, but also the team, because sooner or later the squad will change to such an extent that neither his old nor his new tactics will not work and then the team will start to lose, and the blame will lie on him as the head coach
But it cannot be denied that Klopp's 8 seasons with Liverpool are truly beautiful even though there are some situations that cannot be forced including this season where they are still very likely to get the treble it's just that towards the end of the season the situation becomes unfavorable for Klopp which makes this complicated even though the opportunity is very large to get it.
Now that it's over Klopp's 8 seasons are not short but on the other hand as you said, too long in one place also sometimes does not go well and that's what Klopp now feels so he decided to leave and look for new adventures.
This is a hole for Liverpool because after all losing a coach obviously makes the situation different but on the other hand this is also the right time to start over with a direct overhaul of Liverpool because looking at some of the players now it looks like regeneration will start to be done by the new coach.