A user who was a proxy for another user is still getting timesheet approval action item notifications even though they are no longer setup as a proxy.
Step to reproduce:
Check to make sure the user doesn't have timesheet approval access to the resources they are incorrectly receiving the notifications for.
Note: If you are using a custom process, the proxy user does not need timesheet approval access if you use a timesheet approval process, where you are approving an action item and not a timesheet. See KB000055324 for more details.
See KB000021294 - How do Timesheet Notifications get sent automatically without using a process definition?