It was a Docker for Mac!
There is no clear name indication, that this is a Docker process, so you can't clearly spot it in the Activity Monitor unless you use View -> All Processes, Hierarchically
or view the process origin with ⌘+I.
Stopping Docker releases the resources
Hint : It's possible to see process origin by hitting ⌘+I
Github issue :.
github.com/docker/for-mac/issues/5812Github issue