3.5 and 3.9 are already released or even approached EOL so proper dates need to be here, like in 3.6, 3.7, and 3.8.

Edit: Python next header above the version also looks suspicious.

A specimen with the issue (https://docs.python.org/3.5/whatsnew/changelog.html):

A specimen without the issue (https://docs.python.org/3.7/whatsnew/changelog.html):

Related: gh-92240 (proposes new wording for release date).