Th option to send a "PAID" receipt for an invoice to a customer appears to have been removed from the new invoicing format. Is there a way to send a PAID receipt?

Thanks for getting in touch with the Community, Kkneis.

You can send customers copies of paid invoices which include receipts.

Here's how:
 

1. In your left navigation bar, go to Invoices.
2. Find a paid invoice you'd like to send a receipt for.
3. Under the Action column, use your Drop-Down Arrow (▼) icon and choose Send.
4. Enter any necessary details.
5. When you're ready to send it, select Send.

Once the customer opens their email, they'll see a View receipt button they can use to access the transaction's receipt.

I've also included a detailed resource about working with invoices which may come in handy moving forward: Create & manage invoices

If there's any additional questions, I'm just a post away. Have an awesome Thursday!