So I’ve already began preparing to transfer in a year when I just found out that there is a transfer-specific essay for the common app. I already wrote a great essay with the prompt about an event that marked my transition into adulthood, but will I even be able to use it? Do I still have a choice for an essay topic, because it seems strange for me to write an essay why I want to transfer when the reasons are different for every institution.
No. You can maybe use a condensed version of the essay as an anecdote, but the transfer essay is a specific prompt about your reasons for transferring and what you hope to achieve. While you might not be able to talk about the specific things you are looking for at each university, you must have a broad reason for transferring i.e. major change, different location, etc. Your essay about your transition to adulthood doesn’t answer that.
So just to make sure I follow, transfer students on commonapp have only one choice for a prompt?
Yes