On two separate devices (Android and Windows 7, Opera and Firefox, logged in and logged out) on two separate internet connections, I'm getting pop-ups and pop-unders (this page opened in a new tab, old tab redirected) to spammy sites from at least three different SE sites including this one any time I click on anything on the home page; mobile and desktop sites.
I've had this all day (26th October 2016), haven't seen it before. Seems to be only homepages.
Nothing on any other sites on the same devices, only SE.
But I can't see anything about a problem affecting anyone else. Could it be just me, somehow? I can't see any common factor other than SE.
Here's what the Travel.SE homepage HTML looks like for me. URL is correct, but this doesn't look right at all, it looks like something has compromised it somehow:
And here's the URL that shows if I mouseover the 'Ask' button:
If this is somehow only affecting me, somehow on both my separate devices at once, somehow only affecting SE, can anyone suggest what could possibly be the cause and what I can do about it?
Edit: just had the same thing on this question page after posting it. Ask and edit form pages seem to be unaffected however. Here's what Opera's inspect looks like for this question page for me which triggered two blocked popups and a popunder to a dodgy "make your computer faster" type spam page:
...okay, this page isn't clean either, the preview looks like this: