That looks like bitcoinity.org to me. The volume bars default to bitcoin (mBTC in fact) on bitcoinity.org and it appears that you haven't changed it. Here is the same BitStamp chart after changing volume to USD.
You're right. Not sure why the default volume listed would be denominated in bitcoin when bitcoin is a derivative of the US dollar so the only thing useful for traders is the USD volume. Anyways, on USD volume Bitfinex is down from halving while bitstamp is up.
Finex is a roach motel.