I mentioned this to our department responsible for Shimano in China and there are indeed knock-off Shimano chains, but it is rare to see a fake HG73.

Shimano chains do NOT come with a connecting link (DA did for a bit - not now). You can use either the supplied reinforced pin or get an aftermarket link as you did.

Z99 is a great choice. X9 is a level up with XXSP treated pins and signature XX chamfering.