
Hey all - one of my amazing team members figured this out.
Turns out the notification is coming from OneDrive notification settings.
Open this url (for your tenant): https://TENANTNAME-my.sharepoint.com/?p=22
You need to disable email notification when others upload files to your file requests. The same notifications come in when someone adds files to OneDrive folders, but that email has an unsubscribe/change notifications link.
The new Forms/OneDrive notification email lacks that link.