Seats.io uses the object label to store bookings. If you change the label of a booked object through our designer, that object (e.g. a seat or a booth) will appear to be free again.
E.g. let's say seat "B-24" has been booked. If you rename row "B" to "C", the seat becomes selectable again for ticket buyers. Same thing if you change the seat number "24" to "48".
Therefore, the designer shows a confirmation dialog when you try to edit an object label on a published chart.