Video in iMessage Group is low res for some members

This issue has been reported before (Video thumbnail in iMessage small - Apple Community and others), but no real answer ever seemed to be presented. The suggestions seemed to all assume that the issue was for ALL members of the group, but I can confirm that is not the case with my issue.

(At least) Two members of a large (iPhone/iMessage only) group I am in receive videos in a very low resolution, while other members (myself at the very least) receive them in their full resolution. I have done a fair amount of testing various scenarios to see if something like their internet connection (wifi vs cellular) or a setting on the phone was causing it, and have found nothing that could explain it.

As you can see in the attached photos, even the file size showing on the videos in messages is different (drastically), and the quality of the video is incomparable.

Low Resolution

Full Resolution