http://tonsky.me/blog/atom.xml is valid but not working

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line 597, column 0: style attribute contains potentially dangerous content: background-image: url(./covers/ClojureStream.png) (6 occurrences) [help]

          

line 951, column 0: content should not contain iframe tag (2 occurrences) [help]

          

line 1515, column 40: Two entries with the same value for atom:updated: 2021-12-13T00:00:00+00:00