Is there a way to avoid this (without restarting the service after every
reboot). Is this a bug or a normal behavior?
I have less knowledge of windows.
Do you see shutdown/termination messages in the db logs or windows event logs when the machine is rebooted?
You get the same pid and query, does it also has the same age( time since it started),
I mean is the stats table updated with new data for stale connections or they remain static.
Do you see the same issue when the machine is power cycled.
Maybe windows might be preserving the memory state on disk and reading it back on reboot (like sleep) unless there are instructions to shutdown the db server on reboot. Idk.
What are the state of the connections in pg_stat_activity abd process explorer before and after reboot. The sockets exists and active, or are residual in pg stats only.