It's a PR disaster from Mozilla. I was once a Mozilla rep and I'm ashamed of this. Studies like these should always be turned off by default and the user can opt in voluntarily. But launching Firefox and digging into the preferences to find that I'm enrolled into some studies by default is unethical for me. Sadly, I'll have to switch to Brave or some other privacy concerned browser until I see an official statement and action from Mozilla. I'm sure the management there have something to do with all of this.