Hi there, leemoody1986.
With the rollout of the new QuickBooks Online iOS app update, the invoice layout has been redesigned to align with the platform's streamlined experience. Thus, the ability to add dates directly to product/service lines is still unavailable.
As a workaround, you can enter specific dates from the Description section.

You can also log in to your account via a web browser to utilize the Service Date feature when creating customer invoices. If the Service Date column isn't displayed on your invoice screen, navigate to the Customization tab and enable the option.

If there's anything else you require assistance, please let us know on this thread.