Since updating to Mac OS Catalina and Camera Raw 11.4.1 the Adjustment Brush is not working as it should. After selecting the Adjustment Brush and making some local changes, if I then select "New" for a new local adjustment and begin brushing on the image the "New" radial button automatically switches to "Add" and then new changes are automatically added to the previous local adjustment. The only way around this is to select another tool i.e. "Gradient Filter" and then re-select the "Adjustment Brush". I can then add a new local adjustment. I've flagged this to Adobe via a support chat but still waiting for a response.
iMac (Retina 5K, 27-inch, 2019)
3.6 GHz 8-Core Intel Core i9
48 GB 2667 MHz DDR4
However I have also performed the same upgrade (Catalina and Camera Raw 11.4.1) on my older Macbook Pro and the exact same issue is occurring. I wish I'd only upgraded one thing at a time and then at least I'd know which of the upgrades has caused the issue. My hunch is that the Catalina upgrade is the culprit but still an Adobe problem.
Is there anyway to roll back the Camera Raw update to an earlier version to see if this solves the problem.
We apologize for the issues you are facing with Camera Raw after updating to macOS catalina.
The issue you have described is known and is currently being investigated by the developers for a fix. For more known issues related to Photoshop and Camera raw with macOS Catalina, please refer the below mentioned link.