Recently, I accidentally noticed a feature-wide outage (T345188). Initial symptom of the outage was the image recommendation task pool being drained out and nearly empty. This outage could be noticed more quickly/effectively if we had better monitoring available.
We should think about adding better monitoring for Growth's structured edits. In an initial form, this could include alerting when the number of suggestions drops significantly (more than 20%, for example?). On very tiny wikis, this could still cause random alerts (if a wiki has merely 10 suggestions, 20% is 2 suggestions), but I believe it is better to resolve an unnecessary page rather than continuing to be noticing outages accidentally. If it shows to happen frequently, we can always change the alerting policies to be more accurate, but we gotta start somewhere.