In matches you cannot expect to find all the players real and online because there are millions of players playing on different servers in PUBG and PUBG mobile. So to solve this problem and also to make the game a little easier they create bots for people to kill. Therefore almost every time you would find an enemy in places where you definitely did not see anyone else land. Some of their common traits are that they are foolish and only shoot a single bullet at a time. You can easily outfox them by jumping and crouching. So basically they are enemies generated in remote areas and to fill up the empty spaces.