The DefaultRetryStrategy on JdbcIO retries if the error code is 40001 (deadlock detected).
For some reason PostgreSQL uses code 40P01 instead (40001 being serialization_failure). see PostgreSQL documentation.
It would be great if the DefaultRetryStrategy would return true ("please retry") with this specific additional code.
(tested with 2.28.0 and 2.29.0 master)
I can provide a PR.