How can a Muslim be a "fitnah" for disbelievers, based on Allah Almighty's saying: "Our Lord, make us not a fitnah for those who disbelieve"?

The dominance of disbelievers over a believer is a trial for them because they commit sins through it. It is also possible that the meaning of "a trial for those who disbelieve" (فتنة للذين كفروا) is that they will tempt us away from our religion. The verse encompasses both meanings, as the two meanings do not contradict each other, and it is obligatory to interpret it as including both.