That's actually somewhat of a Safari bug.
Safari has this tendency of opening videos in full screen, if the video is natively embedded (not using a third party video player component), is set to auto play, and isn't flagged specifically for not opening automatically in full screen (this is a Safari specific flag that no other browser requires as no other browser has this stupid default behaviour).
Pechente@feddit.org 15 hours ago
Definitely not great behavior but considering Safari makes up a bunch of their users, they should have really added the playsinline attribute to the video to prevent this. But since this site is made using a pretty crappy site builder, they probably cannot change this until Elementor fixes this bug.