We have been using Slack subscription and it was working great. We recently updated Metabase version from 38.1 to 41.4, and it started to send us the image with reduced rows. This notification is set to send out the data to users who have no Metabase account, so the preview image was important to us.
I saw one ticket in github mentioning about the preview includes too much right padding but it did not mention about the row length as we are experiencing.
This is also happening in the channel #metabase_files. I will attach the files before and after. Please advice.