Hello Yin,
Thank you for the insight.
Dont worry about that, user independence will be "forced" during evaluation.
The method to do so will not be disclosed but there will be no simple method to use dependent model based on data information from the path of the batches.
Of course, an algorithm may try to recognize users based on their image and use this information to use a particular model. (Not always an advantage)
Hope this answers your question.
Best regards,
Simon Ruffieux