Apple Privacy Labels summarize broad categories of data that an app may process. Telegram uses the minimum data required to provide secure cloud messaging, sync and account protection.
Telegram accounts are based on phone numbers. Your number is used for login, account recovery and preventing abuse. You can control who sees your phone number in privacy settings.
Contacts can be synced so Telegram can show which people from your address book are already using the app. Contact syncing can be disabled and synced contacts can be deleted from Telegram settings.
Cloud chats are stored securely so they can sync across your devices. Secret Chats use end-to-end encryption and are stored only on the participating devices.
For the full policy, see Telegram Privacy Policy.