The chances that the next season will be equally successful for Leverkusen are rather low. And it's not only because of the risk of key players getting transferred out. The other top contenders, namely Bayern (the richest club in the Bundesliga), will also be making tactical adjustments and squad investments to make sure they don't get dominated as easily as they did this season.
But there is also the psychological factor at play. In the last 5 seasons, they'd usually end up around 5th-6th place, with 2021-22 being their best one, when they finished 3rd. So no one really expected them to win the league, so they had that overperforming underdog mental boost going on, but that won't be the case next season, when the expectations for them will be set really high, which will bring some extra pressure.
As for their yesterday's game against Eintracht - the 5-1 away win is something to be proud of, given Frankfurt can be a pretty dangerous team. I expected another draw and even made a small bet on it, but things stacked up nicely in favour of Leverkusen. Who knows how it all would end if Marmoush didn't waste his perfect 1 on 1 situation and if Eintracht took the 2-1 lead.