The Revenue total on your event dashboard and the totals shown for individual tickets or add-ons can differ because they summarise different records.
The dashboard Revenue total is built from completed, non-imported ticket, add-on, and donation payments recorded for the event. Recorded refunds reduce that total.
The Revenue > Tickets and Revenue > Add-Ons pages summarise the purchase records currently attached to each item. If you manually remove a ticket or add-on from an attendee, that item may no longer appear in the item-level total even though the original paid order is still part of the event's recorded revenue.
Adding the Tickets and Add-Ons totals together does not include donations.
To reconcile a difference, open Reports > Sales and review the original order, its ticket, add-on, or donation lines, and any refunds. Removing access or removing an item from an attendee is not the same as refunding the payment; use the refund action when money has been returned.