Reset your camera settings or reset your phone to factory settings. Should you restore a backup don't import the settings. My S21U always took nice pictures. If you experience bad quality send picture examples via your Samsung Members app as Error Report to the Samsung developers
Try to use Pro mode and see if it's the same as the Photo mode
Hi @lendelbogdan A number of recommendations to fix the picture quality have already been mentioned. It depends though if you are using point and shoot or if you have tried various settings/modes. The expert raw app is excellent for improving the quality of your images and giving a more professional feel. A bit more detail in this article, I can confirm it is compatible with the S21 Ultra though not the base version or the Plus. https://www.phonearena.com/news/samsung-s22-expert-raw-camera-app-creation-z-fold-3-note-20-ultra-re...
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
My Device- S21 Ultra 5G ( SM-998B/DS ) CSC= BTU , 12GB/256GB
One Ui 4.0,Android 12 Official Version.