Apple has released an update from 10.6.1 to 10.6.2 a few days ago and I almost missed it. As you can see it only seems to update certificates that are about to expire in 2026.
watchOS 10 (Apple Watch 4) precedes watchOS 11 (Apple Watch 5) which was current before the version number jumped to watchOS 26 (Apple Watch 6 and newer).