I got this mail from firebase and 1 month ago I created a website without authentication just for a note-taking website in which way should I update security rules to keep my website running
This warning is specifically about the Security Rules for Firestore, if the deadline is exceeded without the Security Rules containing sufficient Read and Write protection, access to Firestore will be disabled.
An easy fix is to introduce Guest authentication and ensure that only users of your app can read and write with allow read, write: if auth != null
To create a Guest account, this is done with Anonymous sign in methods: https://firebase.google.com/docs/auth/web/anonymous-auth
But it is advised to enhance your Security Rules and use sufficient Auth to differentiate one user from another as a Guest (Anonymous) can be lost and unrecoverable in most situations.