Online store, conversion issues with Ads

Hi folks, so I recently decided to give online ecommerce a go, I created a cool store inspired by a semi-popular gift idea, based on creating a custom 'star map' given a specific location and date/time, which generates how the stars would have looked on that day, shipped to the user in a metal frame, with some other styling/text.

The problem: I have been running ads, trained with pixels etc, it has become much more efficient, however, only about 1 in 50 customers who make it to the checkout page actually purchase. I don't understand why? I have optimised the UI and flow multiple times.
So I am basically draining money.

I made this using Astro/Vite, using the Shopify headless API.
Originally I thought it was the shipping, so I massively lowered that, and the price, I am barely breaking even, not even counting the Cost per Checkout advertising cost.

I have began to experiment with other ad creatives, and tiktok ads.

In short, today I had 50 checkout events, only 1 became a real sale. - Are my ads not trained well enough? Is this a checkout design issue?

The URL is https://starframer.com