I have a configuration of odoo 13.0 with projects, sale, timesheets

I have a user with all timesheets rights that when is connected to the timesheet app by mobile, and he want to create a new entry, he can see the field amount, that consider his economic hour fee.

It's strange because that field is not visible normally, when he is connected to the same view from the PC.

Do you know how to manage it?