Recently my S10 Plus started re-adjusting notification volume. I like to have notification volume slider at about 20%. Typically, the volume would stay there.

Sometime during the last couple of months, the volume started changing. The change is always an increase notification volume. I find this very annoying.

After the volume increases, when I went to Settings>Sounds and Vibration>Volume, I have find that the volume is 70% or more. I reduce it back to 20% which is a more pleasant (less intrusive) level. Several hours or days later, it is back at 70%.

Has anyone else had this problem?

 

That was the first thing that I tried. I have now re-booted (cold) multiple times. This did not resolve the problem.