A suggestion for those that are getting the popups/redirects.
Clear all your cookies and browser history. This will get rid of all your log in status details for every web site you’ve visited on the device so not something to do if you don’t want this to happen.
Now log back in to this site and no other and see if the popups return. Don’t visit another site.
If they do then it’s something relating to this site, if they don’t then it was something to do with your web history. It may not be the same reason for each individual.