NetsJS not found during App Platform build

We have a NestJS based backend using the App Platform.

Deployments were working fine until today, where we got the following error during build:

[2024-01-10 14:23:15] │ Running custom build command: yarn build
[2024-01-10 14:23:15] │ yarn run v1.22.21
[2024-01-10 14:23:15] │ $ rimraf dist
[2024-01-10 14:23:17] │ $ nest build
[2024-01-10 14:23:17] │ /bin/sh: 1: nest: not found
[2024-01-10 14:23:17] │ error Command failed with exit code 127.
[2024-01-10 14:23:17] │ info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
[2024-01-10 14:23:17] │ building: exit status 127
[2024-01-10 14:23:17] │ ERROR: failed to build: exit status 1

What have been changed / what should we change? (Force deployment with clean caches have not worked)

It’s really puzzling since we have a quite identical “test” environment where everything works fine, even after this error occurred, with forced rebuild & clean caches as well.

I have read somewhere that the “@nestjs/cli” would not work as “devDependency” but as a regular “dependency” (and this sound as a plausible reason), but why have not occurred then this error way before?

Any hint / help is really appreciated :) Gabor