Chirag Shah explains what the HADR_DATABASE_WAIT_FOR_TRANSITION_TO_VERSIONING wait type really means:
Recently a customer reported an interesting issue, while querying against recently added readable replica, SELECT statement is shown as suspended and session is shown as waiting on HADR_DATABASE_WAIT_FOR_TRANSITION_TO_VERSIONING
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Upon more investigation, it appeared to be waiting on with a wait type HADR_DATABASE_WAIT_FOR_TRANSITION_TO_VERSIONING
The behavior is by design as mention in the SQL Server product documentation and applicable to all version of SQL Server that supports availability group.
Read on for the explanation.