We just got back from our trip. Granted, not there now (it looks pretty crazy), but it was reasonably busy on some of our days. QS was never more than 20 minutes out for mobile ordering for us, anywhere we looked. We tended to look around 1, so I can't speak to the busiest of lunch times. Did QS dinner once as well, same thing. No complaints here. I would be worried if I were there now tho, woosh!
A side note, the Sunshine place in the land in EPCOT is no longer mobile order. All of the stations are open, get what you want and check out at a register like pre-covid. That was refreshing. I always loved the variety there, so we were grateful to have it back!