Check that: 1. The documentation regarding isolation levels are up to date (both GitHub and https://docs.cloud.google.com/spanner/docs/pgadapter-session-mgmt-commands) 2. Setting a default transaction isolation level works (also using the PG session properties `default_transaction_isolation` and `transaction_isolation`). 3. Showing the current isolation level shows the correct value.
Check that:
default_transaction_isolationandtransaction_isolation).