Are red sex links always distinguishable? Yes, but.......
First, the parents have to be pure in the silver and gold genes. The hen has to have silver and the rooster has to have two golds, otherwise you cannot make red a sex link.
Sometimes the difference is night and day. Sometimes the difference is so small that you have to see the two chicks side by side to be sure which is which. Say you use a Buff Orp rooster for the gold. The red females can look awfully yellow.
You have something else working there. I suspect there is probably dominant white in the mix. Sometimes that can make it harder to determine the difference.
Here is a shot of chicks from my Speckled Sussex rooster over a Delaware hen. There are some others in there so I am not absolutely sure which is the red sex llink pullet. I think it is the one in the top right corner, but it could be the red one on the bottom, or maybe both were. But all three yellow chicks there were males from that mix and were sex link males. You'll notice that one of the males had some reddish down but were easily distinguished from the red females.
I don't know where it was determined that this was a red sex link chick. You cannot tell by looking at a chick if it is a sex link or not. You have to know something about the parents or its origins to have a clue. If the rooster were silver and the hen were gold, the chick of either sex could look a lot like yours.