Hi
Schema diff utilities exclude the SET directive from the function header in compare mode.
Reproducing the problem:

1. Create a copy of the database that has a function containing the SET directive
2. Modify the function and perform the comparison.
   The resulting script lacks the SET directive in the function:

CREATE OR REPLACE FUNCTION bpd.class_del(
iid bigint)
    RETURNS void
    LANGUAGE 'plpgsql'
    COST 100
    VOLATILE SECURITY DEFINER PARALLEL UNSAFE
    <--SET search_path=bpd, err-->
AS $BODY$