There are details not exposed outside of NDA, but my suspicion is that there is a requirement that MAC rotation happen more slowly, like every 15 minutes, and i

There are details not exposed outside of NDA, but my suspicion is that there is a requirement that MAC rotation happen more slowly, like every 15 minutes, and it is a bluetooth MAC and the actual GPS/cell based 'movement' which together trigger an alert. If a bike's Find My support randomized its MAC on every broadcast, it may very well not be possible to tell that it is not a new device each time. That might not be allowed per the licensing agreement, and that might be something that Apple has heuristics to detect and alert on.