Inconsistent visibility of comments beloging to public content of a group

Example: https://stadtgestalten.org/hackhro/praesentationsfolien-schnelleinstieg-balkonsolar/

1. public content is posted by the group
2. a non-member contributes a comment
3. member A contributes a comment
4. member B cannot see the comment of the non-member
   • it is unclear, whether this depends on member B being logged in or not

Somehow the permission logic for displaying a comment seems to be faulty.