Check if your contact is uploaded to Facebook or not.
To check on iPhone, touch on the 3 app to the horizontal line on the.
IPHONE......
...iPhone app and open the menu. Now go to upload contacts in General in Account Settings.
Now check here that the toggle is off or not...
ANDROID.......
...To check on Android phones, open the Facebook app and touch on the three horizontal lines given in the side.
Now scroll down and go to App Settings and see here that the content is toggle off for contact uploads or not...
PC......
Now after logging into the web browser in pc, go to the link below.
https://www.facebook.com/mobile/messenger/contacts
Here, all the contacts will be displayed which have been automatically uploaded by Facebook Messenger.
If you wish, you can also delete them.
Thankyou......