Just ran into this issue and thought I'd be a happy helper and leave the solution for you all.
When you share a link in social media there are certain metadata that you should properly set for the link to be displayed in the most attractive way to collect those precious clicks.
You can find a pretty nice explanation of Open Graph here: neilpatel.com/blog/open-graph-meta-tags
The issue I had was related to caching. I was testing the link by sending it myself in Slack, but apparently Slack was caching that value so I was not seeing the changes.
When I went to different a site I was able to confirm that my changes had been successful and caching was at fault. Even found a site that could be useful for previewing Open Graph: opengraph.xyz