Same pop-up ad keeps popping up in one particular iPhone app

Hello,

Since last week, every time I launch one specific app on my iPhone X this one particular pop-up takes over the screen while making a quick screechy noise. This app is of a well-respected Israeli newspaper I've been visiting for years, and I'm updated to the latest iOS.

Is there anything I can do to stop it from popping up? Or is this something rooted in this specific app? And if so, what exactly do I write to the managers of the site, and what "professional" language do I use to describe it to them?