I have the December patch on my S21 Ultra which was purchased direct from Samsung.
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 5.0,Android 13 .
I'm in the same boat. No December patch following smart switch update to november one 🤔
something happened alright. No OTA and no smart switch detection of latest patch
And this morning, just like that, it updated. Waited for official beginning of winter season