Node.js default version is now 20.x
Change effective on 31 October 2023
The Node.js 18.x version line has been moved to the “Maintenance LTS” status on 2023-10-18, and the “Current” 20.x line became the “Active LTS” on 2023-10-24 as stated on the Node.js release schedule.
To stay in compliance with our stated Node.js support policy, we’ve updated the default version for Node.js builds using heroku-20 and heroku-22 stacks to the 20.x line.
This default change will not apply to builds that have specified a Node.js version (as illustrated here). Specifying a Node.js version is strongly recommended to prevent surprise Node.js version changes during builds.