Assuming a merchant accept Bitcoin,
You as a shopper, place an order, and that merchant did not deliver, or sent to the wrong address, or sent a fake product.
You can not reverse the payment, you can get your bitcoins back, and the only thing you can do it leave a negative feedback.
Of course, there are many other scenarios, like phishing websites, fake websites, selective scams, and so on
What are your thoughts and ideas to prevent these scams.
There are lots of scenarios where chargebacks should be applied but in this case if you want to make a platform like shopify or similar to it you have to send the payments after a month or like Google Adsense where the funds of this month sends at the end of next month, by this you can make the chargebacks and other things and not allowing the merchant to withdraw the profit. Check also Aliexpress they handle the disputes of their customers very well.