We recently discovered some of our databases in an Error State for SQL Server. Microsoft has indicated this is a race condition when failover/restart happens on QDS cleanup. They are working on a bug fix for it. For now, it suggested you set up something that checks your databases to see
Recently, there are have been a few articles about the lack of adoption of Query Store. Note the following: Brent Ozar blogged about it in this article Building SQL ConstantCare®: Why People Aren’t Using Query Store. Erin Stellato blogged about it in this article Why Aren’t You Using Query Store?