TrueCaller is sharing your phone activity by revealing the last time your phone was used to contacts. The application used to identify unknown callers launched in 2009 and has faced a wealth of privacy concerns before.
In addition to making your contacts public, TrueCaller now has another insidious feature at play. If a user installs the app and allows it to sync their contacts, their "Last Seen" time is visible in the application. But it's not the last time you used the app itself like WhatsApp, but rather your actual device. TrueCaller updates your phone usage status without notifying you, which is a nightmare if you want to appear offline.
If you really need to continue using the app, the only solution is to stop the application from running in the background. This means your status would only update when you use the app. Doing this is very simple:
For iPhone, go to Settings and then General, select "Background App Refresh" and look for TrueCaller. Then, simply turn off the green-colored switch.
With Android, go to the Apps menu in Settings, select True Caller and tap "Data usage." Then, tap the three-dot menu button, select "Restrict Background Data," and confirm.
And voilà, your privacy is intact again!