TL;DR: Working as designed, nothing wrong, but if you want it fixed then buy this guy's app.
Pretty bad reporting by MacRumors imo.
Not really. Halide existed long before the Xs's and it's a quality app. While the dev is obviously taking this opportunity to sell a few more copies, their write up goes into depth about what the stock app is actually doing and how they've been able to take advantage of the Xs's new sensor specifically. It's worth the read.