I think there’s something wrong with your solution.
I followed your instructions and set the default shop page to /booking. It works fine when you go directly to shop with the /shop slug.
However, when you clear a cart, the “Return to Shop” button leads me to the problematic page with the /booking slug instead of the /shop slug since you’ve asked me to set it to the /booking slug.
To repeat this error, try adding an item to the cart here, click on the “Review Order” link to go to the cart page. And then clear the cart. After that, you will see the “Return to Shop” button leads you to the problematic default shop (/booking) page.
I’ve built a number of e-commerce shops using other themes using the /shop slug without any issues. This is the first time I encounter such an issues with the shop page.