As more folks are creating more streams, this should be on by default. We should disable them for prod MW streams until T266798: Enable canary events for all streams is ready to do.
Change 709531 had a related patch set uploaded (by Ottomata; author: Ottomata):
[operations/mediawiki-config@master] Enable canary events by default
Change 709531 merged by Ottomata:
Mentioned in SAL (#wikimedia-operations) [2021-08-04T18:10:25Z] <otto@deploy1002> Synchronized wmf-config/InitialiseSettings.php: Enable canary events by default - T287789 (duration: 01m 06s)