Premium Plan= $99/Year that comes with extra security features like the real time IP backlist and country blocking option and also support from highly qualified experts.
Source: https://firebase.google.com/support/guides/security-checklist#api-keys-not-secret
，这一点在91视频中也有详细论述
And the following WebAssembly file:
The tests used in standards for evaluating smoke alarms were developed back in the 1980s. However, despite changes in building materials since then, smoke alarms remain reliable, says Chagger: "They still respond to all the main fires we get today."