BUG #16704: Segmentation Problem - SSL SYSCALL error: EOF detected

The following bug has been logged on the website:

Bug reference: 16704
Logged by: Henryk Korulski
Email address: hko(at)framelogic(dot)pl
PostgreSQL version: 13.0
Operating system: PostgreSQL 13.0 (Debian 13.0-1.pgdg90+1) on x86_64
Description:

We use PG12 Database. After upgrade it to version 13 we have problems with
random query - error SSL SYSCALL error: EOF detected.
It appears on many tables (when selecting data or when inserting). I watch
one select query causes this error. I copied sql query from script and
execute nativly in psql and the problem was the same result with error.

After VACUUM FULL ANALYZE my table, i executed once again my query and query
result was succes. It has been working about 25 minuts and then i got the
same error.

Problem is very similar like
https://www.postgresql.org/message-id/15219.1541773523%40sss.pgh.pa.us

Please HELP.

Best regards
Henryk

My query:
select distinct pam.dscr, p.pojazd_id, m.nazwa, model, nr_rejestracyjny,
(
select array_to_string( array(
select distinct f.firma1_id || '::' || f.nazwa
FROM grupa_pojazdow_pojazd gpp
join grupa_pojazdow gp on gp.grupa_pojazdow_id =
gpp.grupa_pojazdow_id
join firma1 f on gp.firma1_id = f.firma1_id
where gpp.pojazd_id = p.pojazd_id
order by f.firma1_id || '::' || f.nazwa
)
, '|' )
) as firms
from pojazd p
join marka m on m.marka_id = p.marka_id
join pojazd_admin_multi pam on (pam.pojazd_id = p.pojazd_id
and pam.datetime_to is null)
where dscr is not null
order by p.pojazd_id