I’ve offered offline to watch and help debug different settings. While you can’t control if Amazon is having a bad day, you can have tested mitigation techniques.
I’m curious why the UK cohosts didn’t suffer also, so I’m wondering if the platform transmits all the video back to the host and from there out to all participants, so there was a USA-UK-USA-UK set of hops. I’m also curious if Amazon is doing the cohost-host through their own VPN. It’s so awful it has to be designed badly as usually audio is preserved even when video degraded.