Those IDLE connections, might be because the user/application didn't commit the transaction?
IIRC Those would be 'Idle in transaction' ( which are normally bad if numerous, unless your app has a reason for them, as they are the ones which can block things ). Plain 'Idle' are normally connections between transactions, totally normal if you use poolers, or if your app keeps connection opens while it does other things ( like preparing for a transaction ).
There really is a state 'Idle in transaction'? Good to learn.