OpenShift Pipeline fails with "secrets XXX not found." error

Issue

• When executing the pipeline with PipelineRun, a "secrets XXX not found." error message is output, causing the pipeline to fail.
• However, there is no definition of "secrets: XXX" in the PipelineRun manifest.

apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
  annotations:
  name: pipelinerun-001
  generation: 1
  namespace: execute-pipeline
  labels:
    tekton.dev/pipeline: execute-pipeline
spec:
  pipelineRef:
    name: execute-pipeline
  serviceAccountName: pipeline-sa
  workspaces:
    - name: source
      secret:
        secretName: "YYY"

• When "secrets: XXX" is created within the project and the pipeline is executed, the pipeline operates normally.
• Why is the "secrets XXX not found." error message being output?