You're now complaining about noise reduction and the effects of computational photography, which are what most users want to see from the camera; that's the new norm whether it's the iPhone 15, Galaxy S23 or Pixel 8.
If you've never seen a "correctly working" photo from a 15, then it may be that your expectations are not what Apple and other phone makers have opted to provide, compared to the duller appearing lower resolution output from older phone cameras. I'm also presuming you're using the 1x lens with absolutely no digital zoom.
For example, do you think this photo has aggressive noise reduction and plastic features?
It was taken with a $5000 Canon R3 mirrorless camera and $2000 lens and produced by an award-winning photographer who was paid quite well for their work. It is an accurate reflection of what clients and others expect from their photos today (despite the fact I personally find the smoothing rather over-aggressive resulting in a "plastic" look, but I'm not the one paying them for their work.)
People don't want "accurate" photos anymore, they want what they believe the photo "should" look like according to what they see on Instagram and Snapchat.
Sometimes I also think the iPhone's processing is a bit aggressive, but I also know Apple provides ProRAW for less processing and RAW mode via Halide or Lightroom for those who want none at all that they don't add; most people demand photos they can post to social media with zero edits, not even hitting the magic wand button to optimize brightness/contrast.
Computational photography is a sometimes controversial topic, but in the end these are the results consumers demand from their devices.
There is an excellent YouTube video you can search for entitled Smartphone Cameras vs Reality! that covers these issues in great detail.
