うーむ,CommonMark の仕様を眺めてるけど,どうやら > が無くても HTML block になるのは正解っぽい.4.6-6 によると
> Start condition: line begins with the string < or </ followed by one of the strings (case-insensitive) address, article, ...(中略)..., tr, track, ul, followed by a space, a tab, the end of the line, the string >, or the string />.
https://spec.commonmark.org/0.31.2/#html-blocks
なので,> で閉じて無くても改行されていれば良い.
77B830096C1888016B4D7A730BBE9731 B1C5ABAE6391170115F7E72DC0D550BE
CE28B98CAAA92938D7319A8635FEEB03 PE97A4F04EF1B914F6A1698CAA364F693