I'll preface by saying you'd be entirely reasonable in not finding this sufficiently reassuring, but compare the standard terms: https://cdn.deepseek.com/policies/en-US/deepseek-terms-of-us...

To the open platform terms (i.e. for API use): https://cdn.deepseek.com/policies/en-US/deepseek-open-platfo...

The standard terms includes clause 4.3 which grants them the right to retain inputs and outputs for training purposes, and this is missing from their API terms. The standard terms also cover the right to opt out (which you can do from your user settings). No such opt-out exists on the API because it isn't applicable.