Outlook items would have been deleted, but you have deletions disabled. These are new meetings and should not be delted? about outlookgooglecalendarsync

[phw198]

Items are normally only identified for deletion if they were at some point synced to Google and subsequently deleted from there. There are however, situations where it can happen eg due to declining a meeting invite (which deletes it from Outlook) after it has already synced to Google, the organiser revises the time and it appears in Outlook again.

Simplest option is to upgrade to at least 2.10.2 where when you decline the deletion, it will then sync it to the other calendar instead.