Hello,
01. For the cart and checkout pages, You are using WooCommerce Blocks for cart and checkout. You need to replace them with classic shortcodes [woocommerce_cart]
and [woocommerce_checkout]
to make it work. You can do this in Dashboard > Pages.
02. Please deactivate all the 3rd party plugins and activate only theme-required plugins on the site and then check the issue. I am sure your issue will be solved. Then activate the 3rd party plugins one by one and check which plugin is creating the issue for you.
Otherwise, if the issue still exists, then keep the 3rd party plugins deactivated so I can check and give you a possible solution. Also switch the child theme to the parent theme.
Best Regards,