Firebase deploy error: Neither apiKey nor config.authenticator provided (using Stripe)

This is in the context of a firebase app using Stripe with firebase functions.

   "dependencies": {
    "stripe": "^17.2.0",
    "twitter-api-v2": "^1.18.0",
    "firebase-admin": "^12.4.0",
    "firebase-functions": "^6",
    "moment-timezone": "^0.5.45"
  },

All was working fine until I updated all packages to the version shown above.
Since then, when I deploy firebase functions (how come this error is not just a runtime error ??), I get error message:

Error: Neither apiKey nor config.authenticator provided
    at Stripe._setAuthenticator (C:UserswebkoDocumentsAppsAndWebsitesNoderobotfunctionsnode_modulesstripecjsstripe.core.js:166:23)
    at new Stripe (C:UserswebkoDocumentsAppsAndWebsitesNoderobotfunctionsnode_modulesstripecjsstripe.core.js:102:14)
    at Stripe (C:UserswebkoDocumentsAppsAndWebsitesNoderobotfunctionsnode_modulesstripecjsstripe.core.js:58:20)
    at Object.<anonymous> (C:UserswebkoDocumentsAppsAndWebsitesNoderobotfunctionsindex.js:37:33)

The line in question is this one:

const stripe = require('stripe')(process.env.STRIPE_SECRET);

Since the update, it refuses ‘process.env.STRIPE_SECRET’. But works fine when I hardcode the test key as string.

The secret IS set in the environement, and when I run:

 firebase functions:secrets:access STRIPE_SECRET

It correctly shows the secret.

So why passing the secret as ‘process.env.STRIPE_SECRET’ is now a problem ?