Sitemap Couldn't Fetch Error

Hope you guys are doing fine!
My site is showing the site map couldn’t fetch error in Google Search Console. Sometimes show success and the other time couldn’t fetch error. Moreover, it is showing General HTTP error 403.
One of my friends is saying it’s due to a Cloudflare issue. What is the solution to this problem?
Waiting for your fruitful suggestions as I am not able to get out of this issue.
Screen Shot of the issue is attached below.

Do you have any Firewall Rules? Does the request reach your origin server (check your web server logs)?

No Albert, I am not using any firewall.

The 403 could be coming from your origin, and you didn’t answer this:

Just in case, check the Firewall Events Activity Log in the Cloudflare dashboard for your domain. You get to it by clicking “Security” in the left-hand menu for your domain.