We had an interesting boarding experience last week, part of which related to the stairs.

Domestic departure, gate A18, I think. We were there around 45 minutes before departure, having wandered back from T5B. Very few other passengers there, but as soon as we arrived, the gate agent called for us to come through. I explained we were Group 1, not 0, but he did the checks and sent us through to the holding area to wait. Another 2-3 Group 1s followed.
After that, he really policed the boarding groups (very professionally and cheerfully), and there was no call for anyone to check their cabin baggage and pre-board (it was the bigger overhead bins and an unusually light passenger load, too). All in all, it felt far more relaxed and orderly, almost a reversal of the normal boarding experience on SH, with us already 'through' before all the gate-checking passengers.

Anyway, when it was time to board, the gate agent came to switch on the escalator and as a couple of passengers started down the stairs instead, he looked askance at them as if surprised they would wish to use the stairs instead of the escalator. Not an instruction as such, more like disapproval. Not seen that before, so maybe there is something recent about the stairs...