POST 400 (Bad Request) at checkout

I have made a website using Nuxt 3 and Contentful CMS. I was having an issue with validating products at checkout so found out I probably need to use the JSON crawler. I am totally out of my depth with this but eventually solved that issue.

Now, I’m getting the below errors:

This one when I click on the product to open that product’s page:

And this one when I try go through checkout and click place order:

My website is hosted on Netlify here
An example API URL I’m using for the JSON crawler is

Using stripe payment gateway, no customs set, just as standard.

Really lost with this. Can’t find any information online as to why this is happening or how to fix it.

Any help appreciated and I can send code if you let me know what you need.