Referencing submodule from git repository results in error when initializing module during GitLab CI/CD execution

I reference my module as:

source =  "git::https://gitlab.com/dash-infrastructure.git//modules/lambda-apigw-api"

Terraform plan in my CI/CD passess fine. However, in the terraform apply stage, I get the following error:

│ Error: Failed to download module
│ 
│   on main-lambda-apigw-from-module.tf line 1:
│    1: module "lambda_apigw_module" {
│ 
│ Could not download module "lambda_apigw_module"
│ (main-lambda-apigw-from-module.tf:1) source code from
│ "git::https://gitlab.com/dash-infrastructure.git":
│ error downloading
│ 'https://gitlab.com/dash-infrastructure.git':
│ /usr/bin/git exited with 1: error: pathspec 'master' did not match any
│ file(s) known to git

Branch 'master' doesn't even exist in the repository of my module. Any idea what could be the issue?

I am expecting the apply to download my module from the git repo. I tried specifying the ref to my only and default branch - main, even specifying the commit hash with:

source = "git::https://gitlab.com/dash-infrastructure.git//modules/lambda-apigw-api/?ref=main"

But did not help, still same error.

EDIT - RESOLVED

Matt was right - the pipeline executing workflow was indeed the issue. I unintentionally included all 'untracked' files as artifacts of the GitLab CI/CD stage 'terraform plan', which caused this discrepancy. When adding only the artifacts I needed (plans directory), this problem was fixed:

plan lambda develop:
  stage: deploy_lambda
  tags:
    - dash
  needs: 
    - job: build lambda develop
      artifacts: true
  script:
    - cd ./backend/lambda/infrastructure/nonprod
    - mkdir plans
    - *terraform-init-nonprod
    - terraform plan -out plans/plan
  artifacts:
    paths:
    - backend/lambda/infrastructure/nonprod/plans/*

In this situation you would need to specify the git reference which can be a branch, tag, commit sha, etc. Assuming from the latter portion of the question that you intend to reference a branch main:

source = "git::https://gitlab.com/dash-infrastructure.git?ref=main"

and the main branch of the git remote repository would be retrieved through terraform init. More information can be found in the documentation which also links to git reference documentation.

Additionally:
> Terraform plan in my CI/CD passess fine. However, in the terraform apply stage, I get the following error:

This heavily implies there are also issues in the pipeline code executing the workflow portion, and so there may need to be a followup question around that.

Matt was right - the pipeline executing workflow was indeed the issue. I unintentionally included all 'untracked' files as artifacts of the GitLab CI/CD stage 'terraform plan', which caused this discrepancy. When adding only the artifacts I needed (plans directory), this problem was fixed:

plan lambda develop:
  stage: deploy_lambda
  tags:
    - dash
  needs: 
    - job: build lambda develop
      artifacts: true
  script:
    - cd ./backend/lambda/infrastructure/nonprod
    - mkdir plans
    - *terraform-init-nonprod
    - terraform plan -out plans/plan
  artifacts:
    paths:
    - backend/lambda/infrastructure/nonprod/plans/*