Detect the format from the tile data. The two are unambiguous in practice, but set the format explicitly when the source is known - it skips the check and cannot be fooled.
"TILE_FORMAT_MVT"
MapBox Vector Tile, the protobuf format.
"TILE_FORMAT_MLT"
MapLibre Tile, the columnar format. Smaller tiles and faster decoding, but the whole tile is decoded at once - MVT decodes only the layers and attributes the style asks for.
Detect the format from the tile data. The two are unambiguous in practice, but set the format explicitly when the source is known - it skips the check and cannot be fooled.