BUG #17679: REFRESH MATERIALIZED VIEW CONCURRENTLY leaves temporary files?

The following bug has been logged on the website:

Bug reference: 17679
Logged by: Balazs Szilfai
Email address: balazs(at)obiserver(dot)hu
PostgreSQL version: 15.0
Operating system: Debian Linux
Description:

After we upgraded from 14 to 15, the occupied space keeps decreasing.

The following files can be found in the subdirectory of the database: (
/var/lib/postgresql/15/main/base/16457 )
...
-rw-------. 1 postgres postgres 210903040 Nov 6 10:37 t8_4372109.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 14:43 t8_4375122.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 14:43 t8_4375122.2
-rw-------. 1 postgres postgres 434585600 Nov 6 14:43 t8_4375122.3
-rw-------. 1 postgres postgres 210919424 Nov 6 14:44 t8_4375147.1
-rw-------. 1 postgres postgres 210919424 Nov 6 15:22 t8_4375598.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 15:22 t8_4375627.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 15:22 t8_4375627.2
-rw-------. 1 postgres postgres 434585600 Nov 6 15:22 t8_4375627.3
-rw-------. 1 postgres postgres 210960384 Nov 6 18:58 t8_4388673.1
-rw-------. 1 postgres postgres 210960384 Nov 6 18:59 t8_4388712.1
-rw-------. 1 postgres postgres 210960384 Nov 6 19:00 t8_4392884.1
-rw-------. 1 postgres postgres 210968576 Nov 6 20:18 t8_4400972.1
-rw-------. 1 postgres postgres 210976768 Nov 6 23:15 t8_4415109.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 23:16 t8_4415139.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 23:16 t8_4415139.2
-rw-------. 1 postgres postgres 434634752 Nov 6 23:16 t8_4415139.3
-rw-------. 1 postgres postgres 210878464 Nov 6 09:08 t9_4370351.1
-rw-------. 1 postgres postgres 1073741824 Nov 6 09:09 t9_4370380.1
...

200 GB of free storage space disappeared in 24 hours!

Regards,
Balazs