Culprit:
(1) - Snippetizer/index.jelly#L72
(2) - Snippetizer/index.jelly#L75-L89

Reproduction steps:

• Install Pipeline: Groovy or clone https://github.com/jenkinsci/workflow-cps-plugin and then mvn hpi:run
• Create a Pipeline
• Scroll down to the "Pipeline " Section
• Click on "Pipeline Syntax"
• Click on "Generate Pipeline Script"

Screenshot attached about where the feature is displayed.

Proposal
Culprit 1 - https://www.jenkins.io/doc/developer/security/csp/#inline-event-handlers
Culprit 2 - https://www.jenkins.io/doc/developer/security/csp/#inline-javascript-blocks

Testing notes
 - Ensure to reproduce the feature before any change
 - Ensure that you reproduce the feature after you have made the change