If a manager told you that parental leave means lower rating, that's a clear signal the company doesn't value families. With everything that is involved in growing a kid (teaching, empathy, learn to talk in the most simple and direct way), I would be surprised if you are not actually improving. All those interpersonal skills are growing, they might not match directly to your job (e.g. Coding), but will make you a lot…
https://www.dol.gov/agencies/whd/fact-sheets/77b-fmla-protec...
"An employer is prohibited from discriminating or retaliating against an employee or prospective employee for having exercised or attempted to exercise any FMLA right. "
I know of a manager at my company dumb enough to put it in an annual review...needless to say, there's a lawsuit and said manager is no longer w/ the company.