I wonder if this is due to YouTube's www-tampering.js script, which scans the JavaScript environment for patched DOM methods and "suspicious" style / script URI

I wonder if this is due to YouTube's www-tampering.js script, which scans the JavaScript environment for patched DOM methods and "suspicious" style / script URIs, and then collects that information into separate arrays. It isn't entirely clear where that data's going yet, but they are definitely scanning the DOM to check for anything suspicious (read: ad-blocking) added by the user. It's worth running "ytbin.polymer.shared.lib.tampering.info()" in a YouTube tab and checking the results if you get a minute. Never seen this level of persistence from them before.