Usage terms for files uploaded as part of custom GPT

Hello, would like to understand in which terms OpenAI or other third-party services would have access to proprietary data that I would like to upload as part of the Knowledge of a custom GPT that I am building?
I couldn’t find clear documentation of usage terms about uploaded files as such.
Thank you!

Through prompts and interactions they would be able to access any data you upload.

The rule of thumb here is not to upload anything to a public GPT that you wouldn’t post directly to this forum.