Band composit form Sentinel 2 (Band 2; 3; 4 and 8)

Hello people, i’m facing problems whit RGB band composit. Wahat happen, when I composed imagem from Sentinel 2 Band 2, 3, 4 and 8 in QGIS, after I mexessure the pixel wide, I find 56 metre of Pixel

Please friends, help me!

Please can you share some more information on how you obtained the data? is this downloaded data or are you using the QGIS Plugin?