Overbooking - padding not taken into account until all spaces (inventory > 1) are booked for that slot

To reproduce, the product has duration 1 hour, padding 30 minutes, and Inventory more than 1.

Go here and book 1 slot at 15:00 (any day). You’ll see that there are 3 slots left at that time but also all 4 slots left at 14:00 and 16:00. But they should not be available. Only when you book all 4 spaces at 15:00, the slots at 14:00 and 16:00 are not bookable.