I can't speak for Andy, but the issue is in the update to 2020-04-16 for me. The path in the plymouth.service file was not updated correctly. A fresh install with the same snapshot gave the same error. Thus a way to replicate is installing snapshot 2020-04-10 and upgrade to 2020-04-16. Or install snapshot 2020-04-16 fresh. Once the path in plymouth.service is fixed a new upgrade with zypper dup did not throw an issue.