The open descent at station 36 that nobody used until Carl came back, and that becomes a ramp for Agatha.
The stairwell at Station 36 had been open for some time after the ghoul system fell, but nobody had gone down: the entire group waited for Carl's party to return. Daniel Bautista's people were moving in toward the stairwells from elsewhere on the floor.
Elle McGib took the stairs first, swearing off trains. As Carl moved to follow, the steps abruptly turned into a ramp and Agatha rolled her shopping cart past — Imani C moved to intercept and Carl waved her off. Then Loita's summons arrived and Carl went down cursing, Princess Donut still planning her hat fortune for the next floor.
An open stairwell inside the station that reshapes itself into a ramp when Agatha approaches.
Threshold to the next floor and the stage for Agatha's unexplained privilege.