“I agree with @johnzt2020, the error messages do not provide any reasonable explanation, and the hints’ explanations do not give sufficient information. Even though I opened the hints, I couldn’t understand how to proceed and what to do.”
The error message (upon failed test) you will see in the remote tests is usually the best guide to fine-tuning your solution, remember that challenges are git repositories. Soo lets say you removed the secret in the most recent commit, what happens to that same string in any previous commits?
I would suggest checking the repository history and then searching for a tool that is capable of performing git-repo wizardry.