Support
Things worth checking first:
The hours are empty, or it says the weather service did not answer
Apple Weather has no forecast for some coordinates, and it can be briefly unavailable. Try a nearby town. If the app says "No signal" instead, it is showing you the last reading it managed to get, and the age of that reading is on screen.
The reading looks old
Pitot labels the age of what it is showing rather than hiding it. Open the app with a signal and it refreshes. Six hours or older also greys the strip and shows a band, so a stale day can never be mistaken for a fresh one.
It will not use my location
Location is optional and the app is complete without it: search any town on the first screen. If you want it, iOS Settings, Pitot, Location, While Using the App. Pitot asks for approximate accuracy only.
A day reads no-go and I think it should not
Every verdict is measured against the limits on YOUR aircraft, which you set yourself in the aircraft editor, including whether you fly at night. Night is no-go unless you have said you fly at night, and civil twilight is caution. Open the hour to see which factor decided it.
Restoring a purchase
Settings, Restore Purchases. Purchases are tied to your Apple Account, so the same purchase works on your other devices signed in to it.
The widget is empty
A widget draws the last reading the app saved. Open the app once with a signal and the widget fills in at its next refresh.
Deleting everything
Delete the app. Everything it holds is on the device and goes with it.
More about Pitot: its page on madebykamal.app.