RSS feed not working

Another website subscribed to my blog using the RSS feed when my site was originally created with another web creation program. I’ve switched to Sparkle and recreated the website. On the blog page I clicked on the icon that says “copy blog rss feed URL to the clipboard” and provided that link (Weekly Quiz 2023), but it is not working - their site is not refreshing when I update my blog page. The url of the page they want to subscribe to is Weekly Quiz 2023 . Can anyone suggest why this isn’t working? Thanks.

The feed looks ok when viewed here:

Maybe that other website isn’t RSS compliant and is looking for specific content in the RSS feed?