Popup scrolls behind some of the sections on page

Hi.

I’am using modal popup on page, on main domain and on new design subdomain to replace the main domain(rm2020). I didn’t have this issue before when I made the first page but now I noticed, when popup button is clicked, opened section with overlay, scrolls behind some of the containers on the page, including footer.

I checked all z-indexes, I gave button and popup section z index:99 but still the same.

and ideas?

thank you.

The page I need help with: [log in to see the link]