Hunting down ammonia abnormalities is most fun
My take for your measure above is this:
After sixty days underwater all tanks are equal mature regarding ammonia processing if they can demo cycle completion after a full water change. 65 days + demonstrated cycle completion is same bac abilities as Paul's 48 yr old reef. He had seven months and months with fish in, which builds bac populations nicely.
Stopping feeding won't kill them in that short of duration, it may suppress the populations for resurgence later but won't kill, rot in system and remove them. We have massive fallow testing examples where feed was stopped much longer with no ammonia issues
Sw dieoff if applicable isnt enough to overcome 4-8~ ppm ammonia processing abilities daily from any cycled tanks, there's an error here. Post full tank shot if possible
******there is no time a suspected ammonia event occurs in reefing without a visually obvious clue in the tank as long as all fish, medication events, and filthy sandbed waste if any is accounted for. Can't wait to see details on yours
How the first tank updates here will matter on your tank as well. There's similarity in these reports of test only indications, no biology. Can't wait to see pics, pics of tank are better for ammonia testing than actual test kits
Ammonia doesn't come back in the post cycle system ever unless fish, meds, or sandbeds cause it. any true event able to generate above approx six to eight ppm a day, what it takes to surpass a cycled reef with sufficient surface area, will last weeks in duration and will make clouding and smell bigtime.
No tanks so far here had any sustained ammonia ill bet.