The forum configuration here isn’t super friendly on mobile. This is using the Discourse app on Android (which is just a thin wrapper around Chrome):
Basically a bunch of “click here” buttons and no “real” content.
And then once you scroll down, the colors aren’t super readable, with black text on dark blue. I haven’t gotten to the site trust level to post a second screenshot, but it’s easy to reproduce.
Overall it’s probably worth some time working on the site’s Discourse theme for mobile.