It seems to me that you have time series data, and you want to predict a single response (quality). What is quality? Is it a quantitative variable (a real or integer number) or is it a qualitative variable ("reject", "rework", "accept")? What is the machine learning algorithm you're talking about, and what do you want to do with it? Do you want to predict the quality of a new product, given the time series of the predictors recorded during the 20 days? Please provide a reproducible example. That will go a long way towards helping us to help you!
PS I'm curious, which kind of product requires exactly 20 days to be manufactured? I work in heavy industry and here times are so much longer, so I guess it's something smaller and/or simpler than heavy machinery.
PS2 you're most likely right that the AUC approach is the wrong one, but we need a reprex to tell for sure.