Hamburger menu won't open on an iphone

Hi community.
I have a site that is working great except for 1 strange problem. My client has an iphone max and the hamburger menu will not open on his phone. It works great in preview, it works great on my Samsung Galaxy 20… any ideas on what the issue could be?
I do have a popup on the homepage; could that have something to do with it?

Here is my public share link:
(how to access public share link)