If because of some recent mental health situation you cannot perform as good as before, should you mention it when applying for a position? 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?
I don't think you are obligated to discuss health conditions with a potential
employer. Your references discuss your prior work and the importance of your research program. (To the extent they speculate about future performance is irrelevant.)

Go for your dream job and work as hard as you can. Allow your career to evolve as it will.  You shouldn't undermine previous effort by speculating about things that have not happened yet.