@AShirai Thank you for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.
- It is always recommended to use/upgrade your application to latest runtime version of Nodejs. Currently the latest stable version of Node js that is supported on Azure webapp is 18.x for more information you can go through this GitHub article about different NodeJs versions and their respective supported timelines.
- As mentioned in the documentation, App Service follows community support timelines for the lifecycle of the runtime. Once community support for a given language reaches end-of-life, your applications will continue to run unchanged.However, App Service can't provide security patches or related customer support for that runtime version past its end-of-life date.
Feel free to reach back to me if you have any further questions on this.