Checking the vcs history of the file to understand when, and perhaps why, the giant inlined png was added would be a good first step. Usually that will link you

Checking the vcs history of the file to understand when, and perhaps why, the giant inlined png was added would be a good first step. Usually that will link you to bugs and work items in your issue tracker as well. At the very least you'll get the names of the people responsible, and if all else fails you can go ask them. Stick around long enough in one place, and you'll end up doing git blame on some gnarly code and discover that the culprit responsible was... yourself.