On communities pages you have a next page and previous page button. But since the 0.19.3 update. The previous page button is missing. Profiles still have both buttons.
I believe they changed how pages are handled. Before each page had a url with the page number in it, I.E. page=1, page=3, etc. Now they have a seemingly random string instead.
It's missing on Photon UI as well, I notice. I find that to be a mighty interesting observation, and thus I suspect that the underlying cause is the same for both UI's. What that cause is, I don't know enough about Lemmy's code to guess.
Lemmy switched from a simple "page" number to a "cursor". You can't tell what the previous cursor is easily, but you can tell with a page number. I thought it was more complicated than worth it to add back cursor handling because you can just use the back button.