Can you share a screenshot?
I haven't found even a temporary fix for this. Occasionally it will overlap my taskbar, if I can get it to do that again I will post that screenshot as well.
What device are you using - Laptop, desktop, Surface, etc? Which OS are you using? How many monitors? What's the Display Resolution and Scale?
Dell Precision 5570 running windows 10 pro, connected to two monitors through a Dell docking station, set to 2560x1440 (the docking station does not support a resolution higher than that while connected to more than one monitor, they claim that it does but that is a separate headache I'm trying to fix as well) scale is set to 100% on both monitors. There is no change in how Revu acts regardless of the configuration of the listed specs and Revu is the only program on the PC that has this issue.
21.3.0 has been released and rather than fix this problem it has only gotten worse. The overlap into other monitors is still happening with the added bonus of screen overlap at the taskbar, shown below, happening far more often.
I had this issue as well. A quick fix for me was to use the Fullscreen option under the Window tab (or F11) and undo it again. This fixed the taskbar overlap.