To all the people experiencing the redirect/virus warning:
It's most likely not a virus on your phone/system. Still doesn't hurt to run Malwarebytes or some other software to check though.
It's most likely caused by an ad injecting JavaScript into the DOM and triggering the popup/redirect. Very often you will find such redirects when ads gets served because ad-delivery is today usually a multi-step process with several parties involved. This is especially true with targeted ads and real-time ad-bidding networks. In such delivery chains each of the party needs to get some information about the referring party and about the original user to decide which ad to serve or which next part of the chain should take over. Because control from one party to the next party is handled through redirects these information will be encoded in the URL and that's why you'll see this long URL's with various encoded information.
Close all tabs and clear your complete history, cache, cookies, etc of any browsers you are using. This most of the time will fix this. If it persists you can clear all data from any browser/app you use in your settings.
All those failing you can disable JavaScript in your browser, but you will lose some functionality for certain websites if they don't provide a noscript alternative.