I have a 13 mini that I bought nearly 2 years ago, and it's at 91%. I'd be not happy if I had a 14 that's half as old and had even worse battery health. What I've experienced with my 13 is in line with what I've come to expect from iPhone batteries, over the last 15 years.
That said, I charge my battery slowly (using a tiny brick or slow MagSafe charger) partly because I assume it will extend the life of the battery. It's possible that fast-charging is part of what is causing the battery degradation for these iPhone 14 owners.
I think the cycles are the number 1 factor, barring any ridiculously bad scenarios like your phone reaching 200 degrees one day while charging or something extrememly out of the norm. My launch day 14 Pro is still at 100% battery health despite always using fast charging and disabling "optimized battery charging". The main difference between me and the people in the article seems to be the cycle count (i.e. actual battery usage). They charge more than once per day and I charge every couple of days.
Slow charging to the recommended charge percentages is supposed to help but it's really not going to matter much if you're burning through more than one full cycle per day. Hopefully the upward trend of battery capacity continues so charge cycles can drop.
That said, I charge my battery slowly (using a tiny brick or slow MagSafe charger) partly because I assume it will extend the life of the battery. It's possible that fast-charging is part of what is causing the battery degradation for these iPhone 14 owners.