There is no official changelog from Philips Hue yet, but I can draw your attention to a software update for the Hue Bridge. Yesterday evening they seem to have started rolling out firmware version 1.56.1956178040. With this update, the date and time of the last activity are displayed again in the settings under Accessories.
Hue Bridge update brings back popular feature Accessories show date and time again
Accessories show date and time again