Hello,
Thank you for contacting Rank Math support, and sorry for any inconvenience that might have been caused due to that.
I am currently using Chrome and the sitemap page seems to be loading just fine as you can see in my screenshot below:

The sitemap is also validated when submitting it to an XML sitemap validator:

Please follow the steps below:
1. Flush the Sitemap cache by following this video screencast:
https://i.rankmath.com/pipRDp
2. Exclude the Sitemap files of the Rank Math plugin in your caching plugin. The cache could be via a plugin or from the server. For plugins or Cloudflare, please follow this article:
https://rankmath.com/kb/exclude-sitemaps-from-caching/
Let us know how that goes. Looking forward to helping you.
Hello,
We are super happy that we could address your concern.
If you have other issues or questions in the future, please feel free to create a new forum topic, and it will be our pleasure to assist you again.
Thank you.