-- DUOLINGO subscriptions are one-time purchases with no real expiry.
UPDATE user_subscriptions us
SET
    expires_at = TIMESTAMPTZ '9999-12-31 23:59:59+00',
    updated_at = CURRENT_TIMESTAMP
FROM subscription_plans sp
WHERE us.plan_id = sp.id
  AND sp.category = 'DUOLINGO'
  AND us.expires_at < TIMESTAMPTZ '9999-01-01 00:00:00+00';