When hovering over the graph for 'today' you may see a difference in the 'Actual' and 'base' amounts.
This will be down to any overdue Invoices and bills or budgets that have been set which are included in the 'base' figure.
The best place to see this clearly is from the List view Button.
In List View you can review all individual transactions and budgets affecting your cash flow. A toggle allows you to hide upcoming budgeted amounts and display actual transactions only.