You should add like AI players and teammates like how 2k has AI replacement for whenever a person leaves the game. This would fix your botting issues...
it gets complicated in ranked, you would have to do skillbased AI, and then people will start to cyberbully people into leaving in the hopes that the AI is better than them
Its gonna be complicated asf cause of Matchmaking and also agent ability usage. The best thing you can do is do it like CS and let a player who is dead control the AFK player.
cant fix everything. AI bot would be too hard to create because of the different utilities in the game. It will also be hard asf to make sure the difficulty of the bot matches the rank.