Ceph HEALTH_WARN pgs not deep-scrubbed in time.

Issue

• ceph status shows HEALTH_WARN xxx pgs not deep-scrubbed in time.
• The count of PGs not deep-scrubbed in time is rising over time.
• There are no PGs actively deep-scrubbing

# ceph status
          cluster:
            id:     e2bf4810-8eb8-11ee-92a7-fa163e01bab3
            health: HEALTH_WARN
                    85 pgs not deep-scrubbed in time
                    25 pgs not scrubbed in time

          services:
            mon: 5 daemons, quorum mgmt-0,osds-0,mons-0,osds-1,mdss-0 (age 13h)
            mgr: mgmt-0.ewastw(active, since 2w), standbys: osds-0.ivuqwu
            osd: 24 osds: 24 up (since 2w), 24 in (since 2w)
            rgw: 2 daemons active (2 hosts, 1 zones)

          data:
            pools:   6 pools, 161 pgs
            objects: 241 objects, 456 KiB
            usage:   7.8 GiB used, 232 GiB / 240 GiB avail
            pgs:     161 active+clean

• If PGs are both "not deep-scrubbed in time" and actively "scrubbing+deep", see KCS Article 7083351.