Thanks for you reply Pedro.
What I’m actually trying to achieve (and failed for the last week) is to enter %product_cat% into Product or Product Category inputs inside Slug options page so that I would get actual product’s categories in URL. Instead all it does when saving changes is removes both ‘%’ thus changing a variable (%product_cat%) into string -> product_cat.
Desired result
https://domain.com/shop/vegetables/red-potatoes
Actual output
https://domain.com/shop/product_cat/red-potatoes
Thank you once again!