Coutinho has been made to contend with a host of injuries and a loss of form since making a high-profile move to the Nou Camp in January 2018.
The switch was completed a matter of months after the Brazil international submitted a transfer request in a bid to force through a move to the Spanish giants.
But, with Barcelona counting the costs of the coronavirus pandemic, the club are looking to offload a number of players to ease the strain on their wage bill.
Tottenham Hotspur have also been linked with making a move for the attacking midfielder and Stewart feels returning to Liverpool is off the cards due to the way in which he left the club three-and-a-half years ago.
Speaking exclusively to TIF, he said: “Coutinho went for close to £150million and the fans turned against him towards the end.
“Somehow, he has lost form and he was one of the best players in the world. His confidence is maybe low because he isn’t playing week in, week out.
“I don’t see Liverpool revisiting that option.”