Hi there, @Matar.
I'm here to share information about the invoice statuses in QuickBooks Online.
As mentioned by my colleague above the Paid status applies when the invoice received is paid full. While the Closed status, appears to the payments to sales transactions.
If you're referring to the invoice that your customer paid full and it's not a sales transaction the status should be "Paid" in the status column.
You can also, check the invoice statuses and their meaning provided by my colleague KhimG.
For more information, about e-invoicing, you can check this article: Send an invoice.
I've also shared these articles for future reference:
I'm still here if you need further questions or concerns. Have a good day!