For all users, the cart is considered as abandoned after the set cut-off time has passed. The default value for this is X minutes.
For a logged-in user, the cart is tracked right after the product is added to his cart. It is considered abandoned as soon as the cut-off time has passed since adding the product to cart. Whereas, for a guest user, if Add to cart popup modal is enabled then the cart will be abandoned once the email address is entered in popup modal. If Add to cart modal is disabled then the cart can be abandoned only after the guest user reaches the checkout page and mentions his first name, last name, phone number, and email address.