Issue with discount code showing up in cart

[HD_AM]

Hey!

I'm facing an issue with my Shopify store (which is built on the Prestige theme). I'll explain the user journey that is leading to the issue:

1. A user puts some products in the cart and heads to the checkout page. He/she enters an applicable discount code that gets applied. The user does not finish the checkout/transaction.

2. The user goes back to the main website and changes up their products. Now, when the user looks at the cart/cart drawer, he/she automatically sees this discount code visibly applied to the cart. 

My queries are:

1. Is this intended to be the way Shopify/my theme is designed?
2. If not, is there a way for me to fix this? I'd ideally like the discount codes to be applied and reflected only on the checkout page, if possible. 

I'm attaching a screenshot for reference. The code is highlighted in red. 

Thank you!