Hi Sajid,
I made new attempts with sen2cor 2.3.0 (DEM correction I have activated).
Do you also get output values in the range of 1…18600 or so? I understand that they multiply with 10000 but yet the output would not be reflectance at all.
To me it appears that there are outlier pixels from analysis with quartiles in r.univar. but I thought to check with you first.
Thanks
Markus