Storing Telegram chat Id's unencrypted in your bot's database isn't inherently dangerous, as these IDs are not secret and only allow message sending if the user has interacted with your bot. However, they are still unique and static identifiers, so if your database is compromised, a bad actor could potentially map users to interests (if they can decrypt the keywords👨🏾‍💻👨🏾‍💻) or attempt spam/phishing if they can find a way to reach those users. Although the risk is relatively low for small, private bots, chat Id's should still be treated as personally identifiable information, and access to the database should be tightly secured. A good compromise is to use an auto-increment primary key for indexing while storing them in plaintext with proper access controls, encryption for sensitive fields (like keywords), and regular security audits. Overcomplicating with hashed chat Id's and lookup tables is unnecessary unless you're building for high-security environments.