After rebooting - as part of the update process for the 20230501 update - my Pixel 6a got stuck in a boot loop. After a few rounds of this the looping was detected by the startup code, and I was presented with two options: 1) try again or 2) factory reset.
There was also a message stating that a corrupt data partition might be the cause (I did not take any screen dumps or document it at the time, so this is all taken from my slightly flawed human memory). Since neither of these options were particularly tempting to me, I instead switched the phone off. Turning the phone off - and on again after a few minutes - seems to have cured whatever was the problem. This time the phone finished the update process without problems. It now reports the correct os version and works like it should.