No manufacturers ever do manufacture completely by themselves, there are several suppliers that offer components at much much lower cost.
As for all electronics you can easily tell whether you have good or bad quality: the coil whine.
Bad PSUs have a very noisy coil whine and overall shitty wires and soldering spots, i once got an LC PSU which blew up after just 5 minutes, shit happens.
Between 2016 and 2018 i sold over 100 computers with about 10 or 15 Xilence PSUs inside, none of the customers ever called me for a broken PSU or PC and i am sure they run totally fine until today.
I'd like to know though where u got the information from that Xilence PSUs are so bad, own experience or read an article?