Products already got a SKU column, so it doesn’t make sense to add a further ‘Booking SKU’ one.

The actual issue is that the ‘Inventory’ tab is removed by the Bookable Product core implementation, and with it the SKU field it contains.
However, a ‘Booking SKU’ tab is missing on the Bookable Product. Maybe because a WooCommerce Accommodation Product is used, that is based off the Bookable Product?
There may be also other products that extend the Bookable Product class, so this plugin should also show the ‘Booking SKU’ tab for these.