The filter buttons/dropdowns are in no way semantically marked as interactive. This causes keyboard-based web browsers like Qutebrowser (and—I assume—screen readers, which would make this an accessibility issue) to ignore them when picking elements to interact with.
I would expect the buttons to be semantically marked as such.
Simply changing the <div class="dropdown filter-item"> elements to <button class="dropdown filter-item"> via the Inspector seems to do the trick, at least for Qutebrowser, without any bad side-effects that I could see. Alternatively, ARIA roles (e.g. role="button") can be used for this.
