Where did convenience fees for credit option? Why did QB removed it?

I can share some information about the convenience fee feature, @Northeast. 

The convenience fee for credit option is a beta feature in QuickBooks Online (QBO) that is no longer supported. This is due to requirements from the card brand network.

In the meantime, you'll want to create a service item for the convenience fee and manually add it as a line item on your customer's invoice. Here's how:

1. Go to the Gear icon and proceed to the Products and Services. 
2. Click the New button and choose Service.
3. Enter the name of the service item (Convenience Fee).
4. Choose the account used for the convenience fee.
5. Click Save and Close.

See this article for more information about adding a service item in QBO: Add product and service items to QuickBooks Online.

Refer to the following article for more information about credit card processing tips and tricks. 

For any feature updates, I encourage you to visit our QuickBooks blog site from time to time. 

If you need more help with your transactions, let me know in the Reply section below. Take care and stay safe always.

@Northeast 

Are you running a B2B or B2C company? You may consider having a 3rd party solution to integrate with your QBO as a workaround.