Hello Rattlesdencommun,
Welcome to the Community page,
So VAT isn't included in the P&L report as it is a liability. Once an FRS period has been filed the difference between the FRS amount and what the VAT would have been if not on FRS is posted to the Savings by FRS income account which shows on the P&L, but that is only for filed periods, there is no report to show that for an open VAT period in QuickBooks Online. You can leave this as feedback within the main cog wheel, this then gets sent straight to the developers team.