zpool list [-Hpv] [-o property[,...]] [-T d|u] [pool] ... [inverval [count]] s/inverval/interval/
It's man zpool, isn't usage output from command zpool.
A commit references this bug: Author: gbe Date: Mon Jul 20 13:01:19 UTC 2020 New revision: 363362 URL: https://svnweb.freebsd.org/changeset/base/363362 Log: zpool(8): Fix a few typos regarding 'inverval' -> 'interval' PR: 248068 Submitted by: PauAmma <pauamma at gundo dot com> Reviewed by: bcr (mentor) Approved by: bcr (mentor) Differential Revision: https://reviews.freebsd.org/D25719 Changes: head/cddl/contrib/opensolaris/cmd/zpool/zpool.8