I have been trying to track this down for a couple of weeks now. Thanks to this post I can confirm it is the ‘Appspector’ chrome extension (https://chrome.google.com/webstore/detail/appspector/homgcnaoacgigpkkljjjekpignblkeae)
I tested out multiple scenarios and the code will NOT show up when that extension is disabled.
It is a sneaky hack. It will only add the script if you are in the visual mode, or have a builder. If you are viewing/saving the code in the text mode it won’t insert.
This is a sad deal as it has been a reliable plugin for years. Need to find another one now.
