postgresql-server -- MERGE fails to enforce UPDATE or SELECT row security policies

PostgreSQL Project reports

    PostgreSQL 15 introduced the MERGE command, which fails to test
    new rows against row security policies defined for UPDATE and
    SELECT. If UPDATE and SELECT policies forbid some row that
    INSERT policies do not forbid, a user could store such rows.
    Subsequent consequences are application-dependent. This
    affects only databases that have used CREATE POLICY to define
    a row security policy.