Project activity is feature where can be track the activity of the project.
There is a way to turn off project activity from being visible to customer. You can just toggle the OFF button on the right side of the activity.
Project actvitity works smart and auto turn the on/off visible to customer.
How this work?
Example: Not visible to customer discussion is created. After that all project activity logged by this discussion will be marked as not visible to customer. This logic is applied also on tasks,files and timesheets.