The land cover and use classifications of the MapBiomas collection are based on Landsat mosaics. For each IBGE tile 1: 250,000, in each of the evaluated years, a specific mosaic was produced. Each mosaic is produced by the spatial integration of the different Landsat scenes present in each card and by pixel-to-pixel temporal integration. These time intervals were defined according to the variation of the phenology of the vegetal typologies in each of the Brazilian biomes, as a strategy to improve the classification results.
The mosaics are generated in 1: 250,000 IBGE charts for each year containing up to 105 components per pixel, including up to 8 spectral bands plus several spectral index and fraction metrics.
For Collections 2, 3 and 4, given the volume of data it represents (several terabytes) we are still developing a method to facilitate downloading through the MapBiomas page.
For now you can access the Mosaics from Collection 4 directly in Google Earth Engine through the following public collection (asset): projects/mapbiomas-workspace/MOSAICOS/workspace-c3