The shortest way to put it is that you should just enable 10-bit in rc.local for now. You won’t get banding or flickering.
No – because as explained above, the auto switching does not always work. This was added as an experimental feature. The goal is to simplify HDR autoswitching in the future. For now however, we have fixed banding and flickering when colour depth is set properly.
Our focus is to work on improving the HDR autoswitching now, which is why I’m trying to finalise this topic, as the original reported issue is fixed.