Nodejs version on Google App Engine standard - node.js

Question

Googles docs indicate they support the latest LTS of Nodejs, and that they support the latest version of the specified version.
https://cloud.google.com/appengine/docs/standard/nodejs/runtime
it uses the latest stable release of the version you choose.
Currently, NodeJS is on 14 for LTS, and 12.18.4 for version 12. However, App Engine Standard appears to be stuck on 12.16.3 as it's latest version.
Is there any indication of their release cadence? When can we expect an upgrade?
Motivation: I'm trying to setup a typescript monorepo with published packages & App engine. This relies package.json specifying "exports" field, but 12.16 seems not to support it, even behind the --experimental-exports tag.

Answer 1

I have deployed a quickstart with node12 in AppEngine Standard and had the sames results than yours, the current latest TLS for Node seems to be: v12.16.3.
I printed the version with this code:
app.get('/', (req, res) => {
res.status(200).send('Hello, world!>>'+process.version).end();
});
The result was:
This is happening also in the Flexible environment, I faced a similar issue in which is supposed to pick the latest major version, instead always pick a lower, but it is consistent on picking always the same. This seems to be a expected behavior, but it is well worth to know the reason.
I tried setting the specific version 12.18.4 but with no success.
**ERROR**: (gcloud.app.deploy) INVALID_ARGUMENT: The 'package.json' configuration file must specify a supported nodejs12 version that is compatible with the runtime specified in the deployment. Please pin your application to a compatible major version of the runtime via the 'engines.node' property. Supported 'engines.node' values for the runtime 'nodejs12' are: [12.x.x, 12.X.X, 12.x, 12.X, 12.*.*, 12.*, ~12, ~12.0, ~12.0.0, 12, ^12, ^12.0, ^12.0.0, >=12, >=12.0, >=12.0.0, >12.0, >12.0.0, >=1, >=1.0, >=1.0.0, >1, >1.0, >1.0.0, >=2, >=2.0, >=2.0.0, >2, >2.0, >2.0.0, >=3, >=3.0, >=3.0.0, >3, >3.0, >3.0.0, >=4, >=4.0, >=4.0.0, >4, >4.0, >4.0.0, >=5, >=5.0, >=5.0.0, >5, >5.0, >5.0.0, >=6, >=6.0, >=6.0.0, >6, >6.0, >6.0.0, >=7, >=7.0, >=7.0.0, >7, >7.0, >7.0.0, >=8, >=8.0, >=8.0.0, >8, >8.0, >8.0.0, >=9, >=9.0, >=9.0.0, >9, >9.0, >9.0.0, >=10, >=10.0, >=10.0.0, >10, >10.0, >10.0.0, >=11, >=11.0, >=11.0.0, >11, >11.0, >11.0.0].
I think you can file an issue in the Public Issue Tracker, I found this similar in Flexible. This issue could be related to some internal stuff architecture of App Engine. When filing the issue, provide as much information as possible, always sanitizing to avoid sharing sensitive information, such as project ID, passwords, etc.