Hi @sgchan,
Regretfully, there is no WooCommerce version to workaround on this, and besides downgrading WooCommerce version might cause more issues than good.
I’m afraid, we might not able to edit those special WooCommerce pages (cart, checkout, etc.) in the content builder for good since it’s supposed to be edited at the template level (template customization). But I could be wrong and the planned Layout Builder might be the answer.
For now, please make sure the page uses a standard template instead of the blank template, then make sure it’s not created through the builder and should only contain [woocommerce_checkout] .
Thanks,