That’s quite a climb for the old girl. It looked like she barely made it to the top of the steps. She probably lacked the energy to lift her feet over the doorway. Notice how slowly she got up.
That was my first though. Quite an effort for her to get up there.
It appeared to me that she was favoring her left knee while climbing those stairs.
The woman is aging, she was walking like there was some arthritis in the hips.