Im going to either get ignored, or downvoted to hell but…
Bot control.

Their site is the only source the website can be read/scraped and with the influx of ai scrapers ignoring all bot rules they might want to try and kill that.

I havent seen the pop up yet, nor checked out the html dom, but i suspect they, like any website, are getting a huge influx of ai bots doing terrabytes and terrabytes of data transfers