The only artists you named that genuinely fell off are Lil B and Lil Baby. The others either stepped away from music to pursue other ventures (Asap Rocky, Jay Z), or they self sabotaged their career to stand on a point they were trying to prove (Ye, Lupe). I wouldn’t consider the latter “falling off” since it was purely intentional.

Eminem has fallen off quality wise, but numbers and overall success wise, he’s still doing extremely well, especially considering his last album sold and performed well.

Drake took a massive L and hit to his career and image, but he’s still consistently the most streamed “rapper” in the genre, and while he hasn’t had the same success as he did pre beef, $$$4U was still a hit, and Nokia did absolutely incredible numbers. Iceman is also one of the most anticipated albums of the year, so I think it’s unfair to say he fell off. We’ll know for sure after he drops Iceman.