It comes out as individual lines here on Mbin, so OP does seem to have used line breaks. Weird though that on Lemmy, including OP's home instance, it doesn't work.
Does Lemmy maybe have a thing where line breaks work differently in the editor than the final post/comment? Like, Reddit expects you to put two spaces on the previous line for the line break to count, but it will display a line break in the editor by simply pressing enter. So the post as it looks in the editor isn't necessarily how the final product will look like. Does Lemmy do something similar maybe?
They do have a dedicated "Crawler" page.
And they do mention there that they use a website crawler for their Developer Tools and Network features.