I am reproducing this with Version 1.73.104 Chromium: 131.0.6778.204 (Official Build) (64-bit)
I also saw the closed post and verified that solution. Seems like no push notifications work at all, without explicitly enabling Use Google services for push messaging even though that should not be the case:
Looking at this further: Firefox converts the endpoint to its own updates.push.services.mozilla.com and Bravedoes use a Google FQDN as an endpoint, even when using VAPID keys it seems?