A DRM-locked, $400 tea-brewing machine from the Internet of Shit timeline

I’ve stayed at hotels in the last few years that have switched to providing tea via a Keurig (or Keurig-like) device instead of those ancient, inconvenient teabags. The horror.

Can anyone even tell me what’s inside a Keurig cup for the purpose of making tea? It can’t be anything as simple as tea leaves, because there’s nothing left inside after the tea is produced. What sorcery is this?