Yep, this is totally a thing. Two consecutive rounds, and in each of those rounds, out of 64 enemies, the same handful kill me no matter where I am. You can have groups of enemies running to an objective, you can kill all of them, but the one who survives or suddenly comes from a different direction will be the exact same one. Kills must also be consecutive. Their rank doesn't matter. They also can't miss, and they frequently nail you in the head and through things. They will single you out of groups of people. Their Ranger/sentry will prioritise you while they remain invisible to yours.
This happens in every single match.
EDIT: Third match, same deal. Same handful of players. No matter where I was on Stranded, same low rank Xbox players kill me.
Fourth match, same deal.