Landsat has an average resolution of 30 m, so it is common to associate the area of a pixel with 900 m2. However, since the original MapBiomas Argentina data are created following the representation of the GEE standard (Lat/Long and WGS84), it does not use an equivalent projection (equal area). Therefore, the distance from the target to the equator line influences the size of the pixel. Therefore, on a continental scale, the calculation of pixel count and multiplication by 900 m2 should be avoided.
In MapBiomas Argentina, the calculation is performed in Google Earth Engine, applying the ee.Image.pixelArea () function, which generates an image in which the value of each pixel is the area of that pixel in square meters, taking into account possible cartographic distortions.