I have a similar issue, every time a file is synced i get a popup, which gets quite annoying when the share is being actively worked on, resulting in constant popups.
I can’t find anything in settings to disable sync notifications
It does disable the “synced” notification, the problem is it will also disable any other potentially wanted notifications, such as conflict alerts or failed file transfers.
On that settings page, click on Folders. There you can turn off change notifications for each folder separately (or all at once). This does not affect conflict or failure messages.