As a side effect of T115147 which makes mobile skin HTML consistent with desktop HTML the quick surveys on mobile are inserting in the wrong place.
The HTML changes are reflected in https://gerrit.wikimedia.org/r/261218 - the contents of #bodyContent are now wrapped in an element <div id="mw-content-text" lang="en" dir="ltr" class="mw-content-ltr">
There are no surveys currently running but we should get this fixed before the next survey run.
Unit tests will need updating.