Data Domain: Why are there multiple DD cleaning end times?

The following might be observed on Data Domain system:
When fielsys clean status was issued, the cleaning was showing as it has completed:
 

sysadmin@DD# filesys clean status
Cleaning finished at 2022/11/16 15:58:01.

However the filesys clean watch was showing that the cleaning is still running:
 

sysadmin@DD# filesys clean watch
Beginning `filesys clean` monitoring. Use Control -C to stop monitoring.
Cleaning: phase 6 of 6 (summary)
21.4% complete, 448213 GiB free; time: phase 1:20:56, total 35:23:01

The system is working as expected. Here is the cause of the behavior above:
The process by which DD clean reclaims disk space corresponding to recently deleted data ends with the Phase 5 of Cleaning ("copy" phase).
 

The cleaning started at (In the messages.engineering log)

Nov 15 06:00:18 DD ddfs[26748]: NOTICE: MSG-GC-00009: Cleaning started

According to the logs, the cleaning run the copy phase from 05:33 to 16:02 on Nov 16th: (In the ddfs.info logs)

11/16 05:33:41.282811 [7ed1516494b0] GC:S:P:C gc_do_phase: name=copy
11/16 16:02:22.574401 [7ed1516494b0] GC:S:P:C gc_do_phase: exit, name=copy, success=1

At the end of the copy phase, the cleaning completed is added into the logs.  (In the messages.engineering log)

Nov 16 15:58:01 DD ddfs[26748]: NOTICE: MSG-GC-00003: Cleaning completed: 1000065928790016 bytes-live, 0 bytes-dead, 483185510055936 bytes-free.

It is also the completion of the reclaiming of disk space and is the basis for the cleanable calculation for the next run:

Active Tier:
Resource            Size GiB     Used GiB   Avail GiB   Use%   Cleanable GiB*
----------------   ---------   ----------   ---------   ----   --------------
/data: pre-comp            -   57950932.0           -      -                -
/data: post-comp   1381385.5     947033.8    434351.8    69%          21346.9
/ddvar                  49.1         30.4        16.1    65%                -
/ddvar/core           1215.2          2.4      1151.0     0%                -
----------------   ---------   ----------   ---------   ----   --------------
* Estimated based on last cleaning of 2022/11/16 15:58:01.

The Phase 6 of the cleaning called Summary started right after the phase 5 copy had finished. (In the ddfs.info logs)

11/16 16:02:22.575399 [7ed1516494b0] GC:S:P:C gc_do_phase: name=summary
11/16 22:58:45.337126 [7ed1516494b0] GC:S:P:C gc_do_phase: exit, name=summary, success=1

Once the Summary phase finished, the cleaning completion is noted in the log again (In the messages.engineering log)

Nov 16 22:58:45 DD ddfs[26748]: NOTICE: MSG-GC-00005: Cleaning completed: Tier (Active): 40:58:28 elapsed, 7.0% of used space freed, 5.0% of total space freed, 73880278401024 bytes freed

 

The summary phase of cleaning rebuilds summary vectors (which are used as an optimization during ingest of new data). No further disk space reclaiming is happening during this phase.