Go to reddit.com/settings/pri… right now and check the Advertising section near the bottom.

Reddit quietly rolled out a setting called "Ads off Reddit", meaning your data is being shared with advertisers outside Reddit, on other sites and apps. It's opt-in by default, which means most users never touched it.

If you have a Reddit account and haven't manually opted out, you're almost certainly opted in.

Takes 20 seconds to fix.