Adding this device this also appeared to fix my https://github.com/haugene/docker-transmission-openvpn container that recently died. (And not simply giving it elevated privileges, as was previously recommended)
https://github.com/haugene/docker-transmission-openvpn/issues/2883
It appears that these issues all originate from an update to runc (which is used by containerd): https://github.com/containerd/containerd/issues/11078
Luckily I realized that I could Cloudflare-tunnel my Portainer UI out to a long random-nonsense subdomain name.
That allowed me to fix it (and then immediately kill the tunnel – not a fan of exposing Portainer to the internet).