Change.org is for profit, says in their privacy policy that they can sell your data to any third party they want if they merge with another company/sell (aka when they stop profiting), and also says they can give your information (name, address, phone, social media, IP address, etc) to police at any time.
THIS. PLEASE don’t use change.org. change.org are datamining scammers looking to profit on tragedy and oppression. they ask for donations in a way framing it like the donations will go to the cause you signed a petition for, but they actually just go to change.org who DO NOT DO ANYTHING TO HELP THE CAUSES ON THE PETITIONS.
and as op said, they sell your data. when you sign a petition with your name, they have your name (and your ip adddress, and any info you entered) and know what causes you support, and will do everything they can to use that information to make as much profit as possible, including selling information about who signed what to anyone willing to pay. hell, their “criticism” section on their wikipedia page is a mile long and includes this point.
change.org and other similar petition sites can in very rare cases make actual change, but 99% of the time they will not. petitions worth signing that have a greater chance of bringing about actual change are OFFICIAL GOVERNMENT PETITIONS. for example, the usa has whitehouse petitions. many countries have similar official petition sites (feel free to add).
if you still want to sign change.org petitions, PLEASE USE A VPN WHEN DOING SO and do not use your real full name or any other identifying information.