.tip

In transaction mode PgBouncer hands the connection back after every transaction, so anything that lives on the session disappears: SET without LOCAL, advisory locks held across transactions, LISTEN, and named prepared statements on older versions.

SET LOCAL statement_timeout = '2s';  -- survives pooling
SET statement_timeout = '2s';        -- leaks to the next client

Every session-level feature in your code becomes a bug in transaction mode. Before you switch, grep for SET without LOCAL.