Anyone can view your stats unless you change your privacy settings.
If you wish to to make this private In Android:
1. Select the Profile icon
2. Smaller Profile icon
3. Edit Profile and Privacy
4. Select 'No' to 'Share my stats publicly'
If you wish to to make this private In iOS:
1. Select the Profile icon on the bottom right
2. Select the gear icon in the top right
3. Edit Privacy & Messaging
4. Select 'No one' to 'Stats and Charts'