Chromebook PWA not supporting virtual background properly after latest update?

I've been using the PWA with virtual backgrounds on my ASUS C536EA-BI3T3 Chromebook for the last 6 months.  Today when I joined a meeting my image shows up in a circle in the center.  This appears to be related to system requirements - yet I can't find what those requirements are on the site.   And it's been working for months.

What changed, and how do we get it fixed?