You'd expect there to be an option in the camera's settings somewhere, but on my Samsung it's actually not in there that I can see, but rather hidden behind 3 layers of buttons or icons and only findable in selfie mode:
On my s21 if you open the camera and then change to the selfie camera (something I never do) and then touch the filter/touch-up tool icon at the top (little magic wand thing) you get 3 options along the top of the screen: filters, face and colour tone. If you select "Face" one of the options along the bottom is "smoothness", which is my guess as to where the problem lies. You can set the slider down to 0, or else there is an on/off toggle for all of these face modification features (little word "on" in the bottom right corner). This is with a different model (running Android 13, in case that's relevant) but I'm hoping the camera interface on your phone is similar.
And yes, I do find it worrying that the skin smoothing filter was on by default, especially given how many steps were required to even find it. Given the problems that edited photos cause for people's self image I'm rather unhappy about such editing being applied automatically even if people aren't aware of it.
