100% up time is fantasy and realistically not technically achievable. There's so many points of failure, no matter how much redundancy you buy/implement, there will always be a failure point.
My notes and reminders were not syncing between my Apple devices(iOS, iPadOS, watchOS, macOS) and I thought it was internet issues. Restarted all devices then went to sleep. It started to work normally in the morning
This kinda stuff makes me curious what causes it. Is it due to server side upgrades Apple does and then something breaks or is something else causing the issue? Just interesting the root cause of their system/server issues