Gmail stopped loading hidden trackers when I changed this one setting

Your inbox might look clean once spam is filtered out, but that doesn’t mean it is private. Marketing emails and newsletters include tracking pixels that call back to the sender when their images load. Each request registers an open with a timestamp and can be linked to earlier opens to build a profile of when and how often you read. You don’t have to click a link for this to happen, because loading the email images is enough to trigger tracking.