Personally I've had serviceworkers disabled in my browser for several years, as it seemed a pretty obvious supercookie mechanism.

Disabling them doesn't seem to break anything except push notifications - and I also have those disabled, so that's fine with me.

That's a list of service workers on your device. Not sure what point you are making. Service workers are an accepted JavaScript standard across browsers.

For Firefox:

> If you want to see a list of information concerning all the service workers registered on your browser, you can visit about:debugging#/runtime/this-firefox . Below the list of installed extensions you'll find a list of all the service workers you have registered.