Missing thumbnail for Twitter videos

In our community, many share Tweets containing a video.

For most other videos from third-party sources, topic thumbnails are generated, but not for Video-Tweets.

Thumbnails are available in the video object:

https://developer.twitter.com/en/docs/twitter-api/v1/data-dictionary/object-model/extended-entities#tweet-video

Anybody having some input here?

Here’s a tweet with a video

I don’t see a problem?