When you add a sticker over a face or similar moving object in a video clip, tracking is turned on by default. Tracking matches the movement in the clip to make an object appear to be part of the scene. If you want a sticker to stay in a fixed position in your video instead of following movement, you can turn off tracking.
With a video open in the Clips app , tap the clip with the sticker whose tracking you want to turn off.
Tap the sticker, tap Disable Tracking, then tap Done.