It’s intended. It brought Android 12 (S) to a bunch of devices.
https://community.e.foundation/search?q=%221.5.1%22%20order%3Alatest
https://community.e.foundation/t/list-devices-we-plan-to-upgrade-to-e-os-s/42692
Yes, definitely Android 12 
.
That would be what slipped through QA, it seems.