On my Mac,`brew services start mongodb-community@4.2` starts mongod process in unknown port

[Big_Cat_Public_Safety_Act (Why would a 300 kg wild predator be satisfied living inside a cage?)]

~ brew services start mongodb-community@4.2          
==> Successfully started `mongodb-community@4.2` (label: homebrew.mxcl.mongodb-community@4.2)
~ brew services list                       
Name                  Status      User File
mongodb-community@4.2 error  3584 gani ~/Library/LaunchAgents/homebrew.mxcl.mongodb-community@4.2.plist
rabbitmq              started     gani ~/Library/LaunchAgents/homebrew.mxcl.rabbitmq.plist
redis                 started     gani ~/Library/LaunchAgents/homebrew.mxcl.redis.plist