Hello,
Thank you for contacting Rank Math, and sorry for any inconvenience caused.
The pages like Cart, Checkout, MyAccount pages are set to noindex by default.
There is no need to worry about this error.
You can easily exclude the pages from the sitemap, first enable Advanced Mode in the Rank Math dashboard:

Then, add the page id in the option to exclude posts/pages in Rank math > Sitemap Settings > General, as shown:

Here’s a guide to finding the post/page ID inside WordPress: https://mythemeshop.com/blog/how-to-find-post-category-tag-comments-or-user-id-in-wordpress/
Once done, exclude the sitemaps from caching and re-submit the sitemap_index.xml and wait for Google to crawl the sitemap.
I hope this helps. Looking forward to helping you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.