Welcome to the Community, @hoopitz.
I appreciate the detailed steps you took when viewing your sales in the P&L report. The amounts may differ depending on the accounting method used in the report. Let's figure this out and check.
View your Transaction Report again and verify if you choose Accrual as your Accounting method. I've included a sample screenshot below.

If you choose Accrual on your P&L report, the amounts should be the same.
However, it would differ if you choose Cash as your Accounting method. In the example below, the P&L is in the Accrual method while the Transaction Report is in Cash.

An accrual-basis report shows income regardless of whether your customers have paid your invoices, while a cash basis report only shows income if you have received cash.
This may be the reason why you're seeing a less amount on the Transaction Report while everything else shows the correct amounts.
Feel free to get back to me if you have other questions. I'm here to help. Have a good one.