Images posted with a full URL work insert as images. Images posted through a URL shortening service (eg Firebase) do not.
Steps to reproduce
Short URL: https://undefined.page.link/zeuY
full URL: https://lh3.googleusercontent.com/-Lbf5RY2rC7A/W0bXZp2YlqI/AAAAAAAAlnA/Qj90HcyfC0oYT-6WJBLF19hbndYA8CW2wCHMYCw/s0/chrome_2018-07-11_23-21-58.png
I would expect either url to post an image preview. Only the full URL does so.
Screenshot of behavior: https :// undefined.page.link /uJoL
URL gapped as I am new user