In February, UEFA announced that City will be excluded from the Champions League for the 2020-21 and 2021-22 campaigns and have also been fined €30 million ($33m) for "overstating its sponsorship revenue in its accounts" and failing "to cooperate in the investigation," according to findings by the UEFA Adjudicatory Chamber.
The club has appealed the decision but De Bruyne said it will be difficult to stay at the Etihad Stadium without competing in the competition for so long.
"The club has told us that they will appeal the decision, and they are 100% convinced that they are in the right," he told Belgian outlet Het Laatste Nieuws.
"I have confidence in my club: if they are saying it's true, then I believe them. We'll wait and see what happens. Once there's a final decision I will look at it.
"Two years [without Champions League football] would be long. One year is something I might be able to cope with."
Sources have told ESPN that City boss Pep Guardiola is concerned some players would want to leave should they face the prospect of not playing in the Champions League.
During his four-year spell at the club, Guardiola has failed to lead his team past the quarterfinals of the competition.
Before the coronavirus pandemic halted the sport, De Bruyne scored the winner in City's round-of-16 first-leg victory against Real Madrid at the Bernabeu.
Guardiola's contract runs out at the end of next season but De Bruyne said his own future does not depend on his manager staying at the club.
"We'll have to wait, but I'm not going to make a decision based on what he does of course. I have already worked under other managers and when Pep leaves, I have to continue working with someone else," he added.
"The last few years a lot of clubs have enquired, and have asked after my future plans, but I'm very happy at Manchester City. I play for one of the best teams in the world, I play in England, in my eyes from a competitive point of view it's the best league."