Eyedroper is not going back to brush after color pick, it was always working like that. We need it active because somebody may want to add few color swatches...
I talk not about it. If you choose color pick tool and fill you swatches it is ok.
We have settings “activate pen tool when changing color”.
If it is OFF:
1) you paint with brush tool
2) you go eraser
3) you color pick by 
- holding pencil
- holding finger
- double tap on apple pencil gen 2
4) it still stays eraser
If it is ON:
1) you paint with brush tool
2) you go eraser
3) you color pick by 
- holding pencil
- holding finger
- double tap on apple pencil gen 2
4) it goes back to brush tool automatically  right after color picking. It works with first two ways of color picking, but doesn’t work with double tap on pencil.