This is the second time I get this strange notification on my phone. In the notification panel I see a "calendar event notification" (from google) with a strange title, something...hot... Example "Tonight at 9pm party...." and then below another notification as if in the calendar there were that event written. I NEVER came across these notifications and it's 5 years I've been using this account. What's happening?
It could be because someone has gotten hold of your account. It is probably a good idea to visit myaccount.google.com/device-activity and check if there are any unknown devices.
If you're not sure, it is best to just change your password which will force all signed-in devices to sign out.
This could be something that Google added to your calendar due to an email received on Gmail.
From Events from Gmail
When you get an email about an event like a flight, concert, or restaurant reservation, it's added to your calendar automatically. If you don't want events from Gmail on your calendar, you can delete a single event, or change your settings so that events aren't added automatically.
One solution is to disable this feature. From the same source as the above quote
Stop adding events from Gmail automatically
When you turn off the setting to add events from Gmail, all past events added from Gmail will be removed from your calendar. If you turn this setting back on, only events in the future will be added.
- Open Google Calendar.
- In the top right, click Settings Settings and then Settings.
- Next to "Events from Gmail," uncheck the box next to "Add automatically."
- At the bottom of the page, click Save.