Hello,
Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
I added your sitemap to be excluded from caching by your cache plugin on your site then resaved sitemap settings which seems to have fixed the issue.
I also validated the URL with this tool: https://www.xml-sitemaps.com/validate-xml-sitemap.html and it is valid from my end, here is a screenshot: https://i.rankmath.com/yvhXL3
Please check and let us know
Looking forward to helping you. Thank you.
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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.