iCloud Calendar events and entire Calendars disappearing after iOS 18.6.1 and Sonoma 14.7.7 updates

Since updating both my Mac to Sonoma 14.7.7 and iPhone to IOS 18.6.1, my calendars are both disappearing and events are randomly disappearing. I have restored back to August 13 once already because my entire main calendar had disappeared. on 8/16, all of my events from another calendar were missing from 8/8/2025 forward. They were printed and they appeared on my iPhone but were gone from my Mac and from iCloud. I went back to my iPhone, where the events were still appearing, and unchecked and rechecked that calendar and watched the appointments disappear from my iPhone too. This is insane. Is anyone else experiencing this?

[Re-Titled by Moderator]

Original Title: Calendar events and entire calendars randomly disappearing from iCloud/all devices since IOS 18.6.1 and Sonoma 14.7.7