Thanks for your replies.
Got it, I misunderstood what DEPTHAI_LEVEL=DEBUG shows. Not I see, its the device's own resource usage.
Regarding the other processing that happens on my computer - I run depth_preview C++ example from examples without any modification - link. The displayed images are small. I see CPU ranging from 30% to 120% today. Median is around 60%. This is still too high for such a simple app given that main processing happens on device itself, right?
Regarding the default demo app from the installation, I can reproduce the CPU 300%+ very easily on Ubuntu 22.04 on my laptop, but Windows installation and default demo on the same laptop works just fine.
Was the library tested on Ubuntu 22.04? Seems that its something about DepthAI<>Ubuntu 22.04