Imagine the case that because of recent treatments for a mental health problem you cannot perform 100% as good as before. (let's say 70% or 80%) On one hand, mentioning a health issue on its own might have a negative impact on your chance to get a position. On the other hand, you have a CV and a background that reflects your performance in the past and, to some extent, misrepresents your current abilities which are not as good as before.
What is the best solution to this dilemma?