Raspberry Pi 4 ethernet issues with latest UEFI and 11.0_RC6

Hi,

On both a Raspberry Pi 4 and a Pi 400, I've noticed that genet0 ethernet 
doesn't work a good fraction of the time after boot.

This happened infrequently in the past, with older UEFI and older versions 
of NetBSD 11. I've recently updated to the latest UEFI version 1.52 and 
NetBSD 11.0_RC6, and the problem seems to still happen on the Pi 4 and now 
it happens very often on the Pi 400.

When this happens, genet0 is configured, and tcpdump shows packets coming 
in, but nothing goes out.

Occasionally, the network interface can communicate with certain hosts, 
but not others, as if MAC filtering works selectively, or something like 
that.

Has anyone else experienced this yet? If someone who knows how to diagnose 
would like serial console access to the Pi 4 to see what's up when this is 
happening, please reach out.

Thanks!
John