BUG #16540: Possible corrupted file?

The following bug has been logged on the website:

Bug reference:      16540
Logged by:          Paul Hatcher
Email address:      paul.hatcher@sentinelpartners.co.uk
PostgreSQL version: 11.8
Operating system:   Windows Server 2012
Description:

We had a situation where a query that normally ran in 10 seconds instead
never completed.  No conflicts or locks could be seen.  All indexes were
valid and in place.  A full shutdown and restart of the server was done with
no effect.
To test we took a full backup of this system and restored to an identical
alternate system.  Having done this, the alternate system ran the query in
10 seconds.
Final test was to backup and restore back into the production system -
having done this the query returned to running in 10 seconds.  Do you have
any idea what could have caused this?

Thanks
Paul