Pixelated raster, post mosaicing NDVI layer of two S2 datasets

dataset used: S2A_MSIL2A_20190226T051751_N0211_R062_T43PFN_20190226T102424 & S2A_MSIL2A_20190226T051751_N0211_R062_T43PFP_20190226T102424

similar problems were reported here (with proposed solutions):