any wait event for a commit in sync replication?

We are using sync replication, if a session runs an insert, and then
commit, the client is actually waiting for commit to complete, but looks
like this wait doesn't show in pg_stat_activity.

In one session I inserted a row (auto commit), it hangs there.

example=# insert into test_timteout select '1';
^CCancel request sent
WARNING: canceling wait for synchronous replication due to user request
DETAIL: The transaction has already committed locally, but might not have
been replicated to the standby.
INSERT 0 1
example=# select pg_backend_pid();
pg_backend_pid
----------------
19325
(1 row)

During the hung period.
postgres=# select * from pg_stat_activity where pid=19325;
(0 rows)

postgres=#

If there is no event for such commit, anyway to find out such session which
pending on commit(sync replication)