The file is full of 0xFF... Almost, because there are some 0xFE bytes in it.

FF FE FE FE FE FE FF FE FF FE FE FE FF FF FF FF FF FE FE FF FF FF FF FE FF FE FE FE FF FE FE FE FF FE FE FE FF FF FE FE FF FE FF FE FE FE FE FE FF FE FE FE FE FF FF FE FF FE FE FF FE FE FF FE FF FE FF FE FE FE FE FE FF FE FE FF FE FE FE FF FF FE FE FF FE FF FF FE FF FE FF FE FE FE FE FE FF FE FE FF FF FE FE FE FF FE FE FF FE FE FE FF FF FE FE FF FE FF FF FE FF FE FE FF FE FE FE FE FF FE FE FF FF FE FF FF FF FE FF FE FE FE FE FE FF FE FE FE FF FE FF FE FF FE FE FF FE FE FE FE FF FE FE FE FE FF FF FE FF FE FF FE FE FE FE FE FF FE FE FF FF FE FF FE FF FE FE FE FF FF FE FF FF FE FE FF FF FF FF FE FF FE FF FE FE FE FE FE FF FE FE FE FF FE FF FF FF FE FE FF FF FF FF FE FF FE FE FF FE FF FF FF FF FE FE FE FF FE FE FE FF FE FE FE FE FF FE FE FF FE FE FF FF FE FE FE FF FE FE FF FF FF FF FE FF FE FE FF FE FE FF FF FF FE FE FF FF FE FE FF

By converting this to binary (FF = 0, FE = 1), you'll get the flag:

}paws_ym_ni_gniod_uoy_era_tahw{galf or flag{what_are_you_doing_in_my_swap}