TL;DR — Right-hand controller floats off at times. Improved lighting and swapping controllers had no effect.
I just bought my Quest 2 days ago. Loved it so much that I bought 2 more yesterday. Then today, while playing Beat Saber, my right-controller started to wander off. I exited the app and did some testing in the home screen. Shaking it rapidly (as though I were playing Beat Saber) causes it to sometimes float off in another direction.
I thought, perhaps, the lighting in the room could be a problem. Turning on more light had no effect. Then I thought maybe it was an issue with the right-side cameras on the headset. I swapped controller hands (playing the right controller in the left hand, and the left controller in the right hand). Shaking the controllers again resulted in the right controller (now in my left hand) floating off, and the left controller (no in my right hand) responding without issue.
This definitely looks like an issue with the Right controller exclusively.
Related: Oculus Quest losing tracking of right controller often
on Reddit (May 30, 2019)