genuine question

i noticed this has been going on for quite a while, but just need some clarification. are these actual bots or players abusing something or bug? all the usernames are just bot-like and its bothering because its not playable??? its either playing rush, champs or even rivals.

on rush, the pattern is these users will choose similar players and it will change last minute if its a duplicate. then when entering the game, the user is gone and the player will be bot.

on champs/rivals, during kick off they will disconnect few seconds after the game starts and i will get the "match result is currently under review". it doesn't affect my score as it doesn't count but i get these kind of matches so many times, sometimes 4 or 5 matches straight! like its not even playable.

can someone explain this????