Is it a bug that the response of .../api/v3/comment/list?post_id is always empty?

I try to get comment data for my posts via API from my Lemmy instance, but whatever I try on using the GetComments endpoint it delivers an empty array.

For example ... GET https://programming.dev/api/v3/comment/list?post_id=20878811 leads to:

{
  "comments": []
}

I want to ask here, before creating an issue. Has someone a hint?