Seeing this more often now with VE and think it may be a couple different issues (not all on our side) but want to see what we can do to stop it and or lessen impact. This is currently being added to the security queue because I'm a bit concerned about some of the symptoms and worry it could be an injection vulnerability (see below). If we rule out a security concern I'm obviously happy with it being moved.
Editors are making a normal edit and div's are being inserted like
<div id="myEventWatcherDiv" style="display:none;"></div>
often at the start and end of the page.
Googling around it seems they may be inserted by a common 3rd party plugin (divX?) but it is in no way clear. It also seems to be interacting weirdly with VE because it isn't only being inserted it's inserting WITHOUT <nowiki> tags which is what you'd expect if someone put a div in (see https://en.wikipedia.org/w/index.php?title=User:Jalexander/sandbox&diff=564465081&oldid=553572859 ). Could it be being injected somehow around VE and/or parser?