Hi, any mummies using UV sterilizer on MAM bottles and spectra pump parts? I realised mine turned yellow after a month and got me very worried as my boy is still an infant. Anyone experiencing the same?

M using MAM bottles since birth till now 5 months. Also use UV sterilize and Spectra S1. Spectra bottles and pump parts turned yellow about 1.5mths but MAM bottle or part nvr really turn yellow just the teat and the cover turned yellow after 3mths plus near 4 mths i think.