https://dev.twitch.tv/docs/extensions/reference#helper-viewer

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onChanged
Twitch.ext.viewer.onChanged: void function(callback: Function())

This function binds a callback will be invoked when the viewer’s status changes (e.g. if a viewer subscribes and changes their subscription status).

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Cannot tell if broken or only triggers on subscription status change.

IE is it supposed to trigger on role changes? If so it's bugged, if not the documentation needs to document what does cause onChanged to be called