What happens to the data in an Excel sheet that I upload to GPT with a simple model I have made - are there potential data security issues?

I made a simple GPT model to read data from whatever Excel file is loaded by the user. This would typically be anonomysed data about student performance (each student’s performance being represented by a row of performance data). The model then creates a simple message of encouragement for each student commenting on performance. I have been asked to provide a detailed description of how the AI software will process and analyse the data uploaded by the user.