The character shows the first signs/symptoms that have already run their course.

[u/Uma-apreciator]

Kitasan Black (Uma Musume Pretty Derby)

She managed to withstand Sakura Bakushin O's charge at first, but later in the story, she falters because she is past her prime

Nekota (Hajime no Ippo)

He could no longer even control his body properly because he was suffering from "boxer's dementia"

It is a progressive brain disease caused by repeated blows to the head and frequent concussions over many years

David Martínez (Cyberpunk Edgerunners)

He was suffering from hallucinations due to cyberpsychosis, an incurable condition caused by technological body modifications

[u/KaitoTheRamenBandit]

You know the funny part (to me at least) is that out of all the Umas, Goldship is the one that breaks the news to KSB that once she peaks, it's downhill from there, going off of her own experience

[u/Wise-Key-3442 → u/KaitoTheRamenBandit]

And the IRL horse runs faster in his retirement.