We've got 3 production clusters, all on the 'no channel' channel, with node pool auto upgrade enabled. One has had 10.18.x upgrades this week, the others nada.
June 16, 2021
"Control planes and nodes with auto-upgrade enabled will be upgraded from version 1.18 to version 1.18.17-gke.1901 with this release."
"Note: Your clusters might not have the latest released versions. Rollouts begin on the day of the note and take four or more business days to be completed across all Google Cloud zones."
So by June 20 (16+4) we should be upgraded.
Monday notified US has new versions available
Tue notified AU and EU clusters have new version available 1.18.19-gke.1700
Tue US master upgrades to 1.18.17-gke.1901
Wed US nodes upgrade to 1.18.17-gke.1901
AU and EU clusters are still on 1.17.17-gke.4900
Why have the controlplanes on our AU and EU clusters not upgraded?
May 12, 2021
The following control planes and nodes with auto-upgrade enabled will be upgraded with this release:
From version 1.17 to 1.18.17-gke.100.
1 month later still on 1.17
The AU and EU clusters upgraded on the weekend. So two weeks delay from US region to other regions, and 2 months after the release notes said 1.17 clusters would be auto-upgraded. Release notes seem to be completely wrong / irrelevant.