I have asked before but can't remember the answer How do I get a white cotton blouse that has turned yellow white again
I would try oxi-clean
Use Oxyclean, or you can use a granular hydrogen based from Dollar tree. It is the equivalent of Oxyclean at a better ptice.
Darlene: I am a big Oxiclean fan! Soak overnight... and turn blouse a couple of times.
I agree with Oxyclean. I’ve used it many times. Love it.
I bet this will work for clothing too: https://www.hometalk.com/36610742/cleaning-yellowing-pillows-and-more