For more in-depth information on configuring and monitoring tempdb, see these SQLShack articles: The tempdb database, introduction and recommendations How to monitor the SQL Server tempdb database Summary Snaps
All transaction isolation levels on the secondary replicas in SQL Server Always On Availability Groups are mapped to Snapshot Isolation to avoid any blocking. As you know, snapshot isolation uses row versioning. SQL Server databases in Secondary replica also ignore all locking hits. However, you s...