Can you share your configuration? According to the docs, you may:

1. Create PAT with permissions for source code in the tools project (check selected organizations during creation): Use personal access tokens

2. Create Azure Repos/Team Foundation Server service connection: Manage service connections

3. Use it in pipelines: Repository resource definition

   resources:
     repositories:
     - repository: MyAzureReposGitRepository # In a different organization
       endpoint: MyAzureReposGitServiceConnection
       type: git
       name: OtherProject/MyAzureReposGitRepo