Questions, bugs or ideas: email support@wayscale.app. A real person reads every message.
In WayScale, open Settings (the gear on the mountain) and tap Manage subscription, then Cancel Subscription. Or open the iPhone Settings app, tap your name, then Subscriptions. Cancel at least 24 hours before the trial ends and you won't be charged.
Sign in with the same Apple ID, open WayScale and tap Restore on the paywall (or Restore Purchases in Settings).
WayScale keeps your data on your device only. If you allowed Apple Health, your weigh-ins are saved there too, and WayScale can import them on your new phone.
The climber follows your 7-day average, not a single weigh-in, so one day changes it only a little. The weekly change updates once a week, on the weekday you started.
Settings → Delete all data. Deleting the app also removes everything it stored. Data you saved to Apple Health stays in Apple Health until you remove it there.