Lot of sitemap errors in Google Sitemaps

Today I noticed a large number of sitemap errors in Google Sitemaps that seem to be related to the XML formatting of the sitemap.xml pages. The errors are as follows:

Invalid XML tag. This tag was not recognized. Please fix it and resubmit.

Sitemap: https://www.vijaypadiyar.in/sitemap-pt-post-2010-11.xml
Parent tag: urlset
Tag: br

I have taken a screenshot of the Google Sitemaps page and uploaded it here: https://postimg.org/image/6uu2uj3yh/

I am using the latest version of Google XML Sitemaps and WordPress. What could be causing these errors? My WordPress theme is also a paid professional theme.

https://www.ads-software.com/plugins/google-sitemap-generator/