I've been using a Mac account for years. Just checked on my iPad that only posts made on iCloud the last 30 days are on Calendar. None of the older ones appear. I've already turn off and on on settings.
Thanks a lot.
By default, the iOS calendar only syncs events within a specific timeframe, but you can adjust that within the settings.
Open the Mail, Contacts, Calendars section in Settings, and scroll down to the Sync option under Calendars:
Tap that, and you'll get the option to choose how far back you want events to appear, or if you want all events to appear: