I haven't experienced it here but it's become pervasive across the internet:
"What enables these ad redirects to haunt virtually any browser or app at any time, rather than just the sketchy backwaters in which they used to roam? Third-party ad servers that either don't vet ad submissions properly for the JavaScript components that could cause redirects, or get duped by innocent-looking ads that hide their sketchy code.
'These popups are not a new tactic, I've seen them around for at least six to nine months minimum. But people have started talking about it, which I think is a very good thing, because it's a problem,' says Crane Hassold, a threat intelligence manager at PhishLabs, who previously worked as a digital behavior analyst for the FBI. 'Redirecting ads can do different types of things—some of them are just a nuisance, but we’ve also seen redirecting ads in the past that have dropped malware on people’s machines. You’re going to see evolution and adaptation on the threat actor side.'
An ad hijacking your browser like that isn't technically a hack, in the sense that it doesn't exploit a software vulnerability. Instead, it relies on the attacker's ability to submit and run ads that contain redirecting JavaScript. But though they aren't a critical threat to web users yet, redirecting mobile ads could create a jumping off point for attackers. And since you encounter the redirects while browsing on even prominent, legitimate sites, there's nowhere to hide. Sometimes the ads are even designed to block your "Back" button, or keep redirecting when you try to close them, making it difficult to escape without having to restart the browser.
'I do think it's new that the ads are so pervasive and are on first-tier publishers," says Anil Dash, CEO of the software engineering firm Fog Creek. "These things used to be relegated to garbage sites, now it's happening on the New York Times.'"
https://www.wired.com/story/pop-up-mobile-ads-surge-as-sites-scramble-to-stop-them/
ETA: I usually don't get these redirects when I use my 3 different adblockers at once. I wish they were also available for iphone but they're not so the best solution I've found on mobile so far is using the browser, Ghostery for ios.
