zpool status Removal of vdev 1 copied ... in ... completed on ... memory used for removed device mappings

freebsd-questions:

I have a FreeBSD machine:

2022-04-11 08:26:24 toor@f1 ~
# freebsd-version ; uname -a
12.3-RELEASE-p4
FreeBSD f1.tracy.holgerdanske.com 12.3-RELEASE-p3 FreeBSD 
12.3-RELEASE-p3 GENERIC  amd64


With a ZFS pool:

2022-04-11 08:28:00 toor@f1 ~
# zpool status z6000a
   pool: z6000a
  state: ONLINE
status: Some supported features are not enabled on the pool. The pool can
	still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
	the pool may no longer be accessible by software that does not support
	the features. See zpool-features(7) for details.
   scan: scrub in progress since Sun Apr 10 19:55:12 2022
	3.81G scanned at 37.1M/s, 0 issued at 0/s, 2.65T total
	0 repaired, 0.00% done, no estimated completion time
remove: Removal of vdev 1 copied 39.9G in 0h4m, completed on Wed Feb 17 
16:45:57 2021
     1.20M memory used for removed device mappings
config:

	NAME              STATE     READ WRITE CKSUM
	z6000a            ONLINE       0     0     0
	  gpt/z6000a.eli  ONLINE       0     0     0
	cache
	  gpt/z60a.eli    ONLINE       0     0     0

errors: No known data errors


gpt/z6000a is a large partition on a 6 TB HDD used as a backup/ 
replication target.  gpt/z60a is a large partition on a 60 GB SSD used 
as a cache.  In the past, I accidentally added gpt/z60a.eli as a striped 
vdev, rather than as a cache vdev.  I then removed it.  How do I get rid 
of the following message?

remove: Removal of vdev 1 copied 39.9G in 0h4m, completed on Wed Feb 17 
16:45:57 2021
     1.20M memory used for removed device mappings


David