You explicitly gave them permission to do so when you agreed to the EULA at the time you downloaded it. If you have a problem with that, feel free to delete Mozilla and move on with your life. Mozilla doesn’t owe you anything.

What’s the point of making it opt in when only the most paranoid users are going to be concerned enough about this to opt out

“We came out with this new feature to help us improve our product, but we’re deliberately kneecapping it on day one by making it opt-in” lol

If you are that paranoid about your data just go use Tor through a vpn already