Milos Radivojevic notes some changes in Query Store with SQL Server 2019 CTP 3.0:
In addition to default value, the minimum number of query executions in the AUTOquery_capture_mode for storing the query, its plan(s) and runtime statistics in SQL Server 2019 has been increased from 3 to 30. That means, Query Store does not store anything for first 29 query executions. It reserves query_ids, but it starts storing execution plan and runtime stats from 30thexecution in a single day.
These look like reasonable changes to me.