Chosen Solution

As you can see in the image my fitbit charge 3 has three ribbon cables coming from the screen where the one of the teardown has only 2. My replacement screen also only has two. Can anyone explain this? What kind of connector is this?

Are you sure this is an authentic fitbit? it could be a knockoff that for what ever reason needed another cable

You have a special edition Charge 3. You see them on occasion. If you have the sticker on the back of the screen, that should be removable and then you can apply it to the back of a replacement screen. Otherwise, ignore it and the payment option will just stop working. It’s not a big deal if it does so unless you have a use for it.