Code splitting with serverless build doesn't really work

Issue description

Hi!

I'm trying to update my sls repo to v4 and move from serverless-esbuild to serverless native build I have pretty simple setup with 2 lambdas with different dependencies in one repo.

serverless v3

My serverless.yml for v3 looks like that:

custom:
    target: node20
    external:
      - sharp
    exclude:
      - '@aws-sdk/client-dynamodb'
      - '@aws-sdk/client-lambda'
      - '@aws-sdk/client-s3'
      - '@aws-sdk/lib-dynamodb'
      - encoding

and I have this output:

As you can see sharp-statistics zip archive is way bigger, because it includes sharp package dependency

serverless v4

In v4 I have almost the same serverless.yml configuration related to build:

build:
  esbuild:
    target: node20
    external:
      - sharp
    exclude:
      - '@aws-sdk/client-dynamodb'
      - '@aws-sdk/client-lambda'
      - '@aws-sdk/client-s3'
      - '@aws-sdk/lib-dynamodb'
      - encoding

But sls package output is very different:

For some reason telegram-telegram-bot includes a sharp dependency in its build, even though the codebase is exactly the same as the v3 branch, and this lambda doesn't use the sharp package at all.

It would be great if you could help me find the reason for different behavior of sls package and fix it

You can find my repo here: https://github.com/EugeneDraitsev/telegram-bot-app It has 2 branches: master with v3 and serverless-v4 with v4

Context

No response