As the time of this report, at https://datatracker.ietf.org/meeting/121/session/dinrg, if view is large enough, the chatlog button here

points to the raw json in the materials rather than the digested view at the document page. It should point to the document page instead.

If the view is narrower (such as on a phone), the chatlog link

is to https://datatracker.ietf.org/meeting/121/session/session.chat_room_url, which 404s.

The workaround until these are fixed is to look for the links to the chatlogs further down on the page.