My understanding is that once a project (let's say, a Next.js site I'm hosting on Netlify) has been built and deployed, the Node version is not relevant any more since the assets have already been built and made available. Is that correct?
I currently have a project where I needed to upgrade the Node version in the code, the CI, and a production instance. My current application hosted on Netlify ran on Node 16. I updated the code locally and the CI as well to adopt version 19, and settings on Netlify at the end. However, the older site did not stop functioning, probably because the public assets have nothing to do with what the Node version is now set to.
But are there any caveats to this? Assuming the production instance never gets deployed to again.
The comment by @jonrsharpe answer's my question, therefore moving to close
It depends. If what's deployed is purely static built assets, then: no, the Node version doesn't matter at runtime. But you may be doing that build in Netlify, or even using things like their lambda functions which do use Node at run time