I remember when that man walked out of the shop. But when the door was about to close again, Elizabeth reached out and grabbed the doorknob. That is to say, the camera has been switched to Elizabeth's hand.
I agree with upstairs, and I also think this action is a hint that Elizabeth says goodbye to her former self.
At that time, Isabella still had the idea of meeting the man who was in love with her at the blueberry pie store. But in her heart, she knows the end of this relationship, and wants to step out of this relationship to be a new self and find new love.
In other words, entering the store represents nostalgia for this ended relationship. Turning around is a new beginning to find a happy life.
I understand that director Wong Kar-wai used such a set of shots here to insinuate some choices that often happen in our lives into movies.