For those with NDA access, see also the more detailed investigation at https://phabricator.wikimedia.org/T157404 (nothing super secret about the topic per se, it's just that some partial IP data was examined in the process, so the task was set to non-public to avoid privacy concerns)
When filing that task half a year ago, I wrote that "At about 0.5% of our total human views currently, they start to matter for overall traffic trend analysis etc." They have since increased and, as can be gleaned from Kaldari's remarks, do indeed affect our global stats markedly now. I have started to remove them in the pageviews stats and trends I'm preparing, will follow up with more detail on Phabricator.