By default, Reclaim will never send you notifications for synced copies of events created via Calendar Sync. However, if you're receiving notifications via Apple's Calendar app for those synced events, it's possible that you're running into a bug associated with Apple's settings for event notifications.
The problem, and how to fix it
When Reclaim creates synced events, as mentioned above, those events get set to never notify you. However, Apple Calendar has a bug where the "general setting" for its calendar notifications will override what Reclaim has set on synced events and notify you anyways.
Here's how to fix it:
On your Apple device, go to Settings
Tap or click on Calendar
Tap or click on Default Alert Times
Tap or click on Events, and select None as the value
Now you'll need to delete and resync your Google Calendar from your Apple device. To start, go back to Calendar.
Tap or click on Accounts
Locate the account / email where the offending calendar is and tap or click on it
Next to Calendars, toggle the switch off
Tap or click on Delete from My iPhone
Toggle the Calendars switch back on
Go back to your Apple Calendar and wait for your calendar to resync all events. Now, your notifications should all be set to honor Reclaim's settings!