Coutinho completed his loan spell at Bayern by winning the Champions League title after a 1-0 victory over Paris Saint-Germain in the final on Sunday.
The Brazil international is expected to make a permanent move from Barcelona this close season, the former Liverpool star linked with a return to the Premier League.
Coutinho, who came off the bench against PSG, said he was eager for a strong 2020-21 season – but he is unsure where that will be.
"I haven't thought about this. I have to go back and I want to work hard to have a great year," he told Movistar+.
"I don't know if [it will be] in Barcelona."
As Barca finished 2019-20 trophy-less, Coutinho won a treble at Bayern, who crushed the LaLiga giants 8-2 in the quarter-finals of the Champions League.
Coutinho scored a brace in that game and also came off the bench against PSG as Kingsley Coman's second-half header was enough in the final.
It meant PSG were denied a maiden Champions League title, but Coutinho still had praise for his international team-mate Neymar.
"I told him that he had a great season and he is going to fight for this and to be the best in the world," he said.