It abandoned the Material Design web components project, which, I think, attracted some Polymer people.
Speaking of Polymer, it has evolved into Lit; but I understand there is no more support for that project from Google. Lit has joined the OpenJS foundation to stay afloat. The Googlers that used to work on Lit, and on Material Design web components have mostly left.
Also, remember the Workbox project? A simple setup for service workers? It's barely alive.