PG Bug reporting form <noreply(at)postgresql(dot)org> writes:
> I believe I found a bug that causes EXPLAIN to produce JSON with
> duplicate "Workers" arrays when the following conditions are met:
Yeah ... this is fixed for v13 but we felt that back-patching such a
change might cause more pain than benefit. See
https://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=100136849
regards, tom lane