Simplepie.php XML Doc invalid

Hello

I get the following error messages on my site for this feed

[02-Mar-2020 10:40:36 UTC] PHP Notice: This XML document is invalid, likely due to invalid characters. XML error: > required at line 20, column 127 in /home/wordpres/public_html/shepherd.herts.sch.uk/wp-includes/class-simplepie.php on line 1421
[02-Mar-2020 10:40:36 UTC] Feedzy RSS Feeds – related feed: https://shepherdprimaryschool.edublogs.org/rss – Error message: This XML document is invalid, likely due to invalid characters. XML error: > required at line 20, column 127

However on another site using the same feed it works fine.

Is there a hosting issue that may be preventing the feed from coming through please?

W3C validator says it’s a valid feed

https://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Fshepherdprimaryschool.edublogs.org%2Ffeed

Many thanks for any help !