The photo is a little dark, and, due to it being from a smartphone, the phone has applied its own corrections like noise reduction, so the result is this:
The main problem with smartphone photos is that the sensor is small, so this will cause problems when enlarged, as you can see in your photo.
Thank you for the feedback! I appreciate you explaining the limitations of smartphone sensors. I’ll keep this in mind for future photos and work on improving the lighting and quality of this one. Your advice is really helpful—thanks again!