rebooting a standby causes it go down on pgpool side

Hi all,
I've three identical machines, running pgpool 4.6.2, postgres 17, one
primary (pg1) and two standby pg2 and pg3.

The initial situation is:

% ssh pg1 'sudo -u postgres pcp_node_info -U pgpool'
pg1 5432 1 0.166667 waiting up primary primary 0 none none 2025-10-30 11:01:05
pg2 5432 1 0.333333 waiting up standby standby 0 streaming async
2025-10-30 11:01:05
pg3 5432 1 0.500000 waiting up standby standby 0 streaming async
2025-10-30 11:01:05

% ssh pg2 'sudo -u postgres pcp_node_info -U pgpool'
pg1 5432 1 0.166667 waiting up primary primary 0 none none 2025-10-30 11:01:10
pg2 5432 1 0.333333 waiting up standby standby 0 streaming async
2025-10-30 11:01:10
pg3 5432 1 0.500000 waiting up standby standby 0 streaming async
2025-10-30 11:01:10

% ssh pg3 'sudo -u postgres pcp_node_info -U pgpool'
pg1 5432 1 0.166667 waiting up primary primary 0 none none 2025-10-30 11:01:10
pg2 5432 1 0.333333 waiting up standby standby 0 streaming async
2025-10-30 11:01:10
pg3 5432 1 0.500000 waiting up standby standby 0 streaming async
2025-10-30 11:01:10

I don't know why, the machines are reported as "waiting up" even if
eveything is working fine and I've waited several minutes without
having any change in the status.

Now, if I reboot a standby, let's say node 3, it comes up with a "down
up" status and the only mode I've to make pgpool see the node as
healthy again is to run pcp_attach_node.

% ssh pg3 'sudo reboot'

% ssh pg1 'sudo -u postgres pcp_node_info -U pgpool'
pg1 5432 1 0.166667 waiting up primary primary 0 none none 2025-10-30 11:01:05
pg2 5432 1 0.333333 waiting up standby standby 0 streaming async
2025-10-30 11:01:05
pg3 5432 3 0.500000 down up standby standby 0 streaming async
2025-10-30 11:08:21

% ssh pg2 'sudo -u postgres pcp_node_info -U pgpool'
pg1 5432 1 0.166667 waiting up primary primary 0 none none 2025-10-30 11:01:10
pg2 5432 1 0.333333 waiting up standby standby 0 streaming async
2025-10-30 11:01:10
pg3 5432 3 0.500000 down up standby standby 0 streaming async
2025-10-30 11:08:21

% ssh pg3 'sudo -u postgres pcp_node_info -U pgpool'
pg1 5432 1 0.166667 waiting up primary primary 0 none none 2025-10-30 11:09:08
pg2 5432 1 0.333333 waiting up standby standby 0 streaming async
2025-10-30 11:09:08
pg3 5432 3 0.500000 down up standby standby 0 streaming async
2025-10-30 11:09:08

Is this normal? Because the node is streaming regularly, so it is fine
on the postgres side and it should also take over its last status at
boot (i.e, at least waiting).

Anything I should dig for?

Thanks,
Luca