Look on my works, ye Mighty, and despair!

After my heroic efforts in generating script approval hashes, I discovered that there was now a global option to turn it off entirely:

Or, using CasC:

security:
  globalJobDslSecurityConfiguration:
    useScriptSecurity: false

Turning this off is pretty safe, as long as you aren’t running a public instance, and have a review process for any Jenkinsfiles being added.