Pro-tip to those unused to mastodon web-ui: you can click the eye on the top right of the center column (next to Back) to expand all posts at once.
The fade effect on the line of text shown is in line with how "click to show more" is done in many places all over the web. It took me a thoroughly minimal amount of mental capacity to realize there was more. I clicked, and got more. It's really not that confusing.