A bit of a follow up, I verified it happens in a 32 bit (i686) Debian sid chroot and not in 32 bit Debian Bullseye (actual install on hardware).
Should I be properly reporting this on the issue tracker? I don't have an account on the coreboot redmine tracker, though I probably should make one. I can't even find where the upstream vboot utils issue tracker is, unless it's just under the main chromium/chromiumos? I didn't post the end of the error message, but it's from building in vboot_lib.
Branden