Incomplete member list
Recently (although I can’t say precisely when) Fractal nightly started giving incomplete room member lists. This means that going to the room details view will show way less members than there actually are in the room, and that autocomplete will not work for people not shown in that list.
@jwestman investigated and reported that the issue would come from synapse occasionally sending an empty string rather than null for the avatar_url at the joined_members endpoint, breaking deserialization.