Disclose past medical leave in applications/interviews?

I know there are plenty of posts on here asking what background checks cover, and to be clear - I am not intending to lie about my past position, salary, etc. But I'm in kind of an odd position - I had to take FMLA leave (medical leave) during my last job, more than once actually, and I'm trying to decide whether I need to disclose it in job applications or interviews. I know that my past employer won't reveal this during an employment or reference check, and it's something I would rather not bring it up myself, partially because I think it's a red flag and partially just because it's uncomfortable to talk about, but I will do so if necessary. What I'm trying to gauge is whether it is necessary.

So I guess two questions: 1. Is it dishonest to not disclose this in applications/interviews? And 2. How likely am I to have to submit every past W2? (I think this is only way it would come up - I have a salary drop during 2 separate years from taking unpaid leave). Really torn over what to do and would appreciate any advice.