On the new mobile chat, the "Loading [Room name], Just a second" message looks old, out of place and bad:
In fact, it was taken directly from the old chat interface:
It should loose the beige background and the shadow on the box IMO.
(As a technical side note: why not get rid of it entirely, and embed the initial messages and other data in the page, so that it does not need to make an additional network request ?)