The jet bridges aren't functioning properly.
The ""bussing" situation is exactly as TK787 has explained. If the incoming plane is on a domestic flight but will switch to an international one afterwards, they park near to the international gate (w/o and prior docking to the dedicated jetway), disembark the passengers and then dock to the jetway to board the international pax. The domestic wing (Pier-G) is situated at the very southeast end of the terminal and they have no luxury to re-shift the plane from Pier-G area to the other 4 Piers' area (which are the international ones).
It's simply a bad (but perhaps unavoidable) terminal design.
I experienced this exact situation a few days ago an thought it was very strange. We were bussed from the domestic gates to B gates on departure, and bussed from the inner F gates to domestic arrival on return. Of course I understand the reasoning, but don't feel very convinced that there is no reasonable alternative. I wonder if minimizing the transfer of aircraft from domestic to international operations so regularly would decrease this occurrence or even if there could be a pathway for arrivals to F gates to quickly get into the domestic arrivals section within the terminal, or even a rule that a domestic arriving aircraft moving on to an international departure has to dock at F gates so that the bussing distance is minimal. Perhaps this is not though to be worth the hassle, but to passengers the recurring blabber was that we are back with the Ataturk bussing nonsense, and it did indeed for that moment feel exactly the same as the old airport, especially since they are the same busses.
On a different note, the space of the terminal is really amazing and the experience is a totally different one. I personally don't mind all the walking as the space is fair comfortable and there is a lot of pedestrian spotting to be done, the fun thing about Istanbul is the uncommon airlines that fly there and the diverse fleet TK operates. There is an IGA lounge used by currently all other airlines, however there seems to be a SkyTeam lounge under construction, it is also on all the airport maps. No sign of a priority pass lounge or anything for EK, HSBC, etc, so quite a different set up than Ataturk so far, which lost its SkyTeam lounge in the last months.
Noticed a few signage issues, in piers A and G gate '11' disappear from the signs at some point. It is not difficult to know where it is if you can count, but just strange. Also no signs for the IGA lounge and the maneuvering to the food court area is a little weird. I also noticed the significant topography mentioned on the airport thread a couple of weeks ago, it is very noticeably during taxiing, which was never shorter than 20mins during my few flights in the past month. The approach is cleaner and clearly more efficient than the old airport, but it is still slow, and the combination of long approach and even longer taxi times make short flights to/from the airport a little humorous. Beautiful view of the city on arrival and departure, so there is that.
Very excited to see how this airport will age in the coming 5-10 years.
There will come a time when you believe everything is finished - that will be the beginning.