What to do if after resubmitting a bug, the developer claims it is not a bug?

In that case, I will take the following actions:

1. Recheck the bug: Ensure that the bug reproduces in the reported test environment (product version, environment, OS, browser, etc.) using the reproduction steps from the bug report.
2. Clarify reproduction steps: Maybe the problem lies in inaccuracies or incompleteness of the description of the steps. I will try to make them as detailed and unambiguous as possible.
3. Gather additional information: Logs, screenshots/video recordings, network requests (if applicable), database data. This will help provide more context to the developer.
4. Check similar cases: Were there similar bugs in the past? How were they resolved?
5. Communicate directly with the developer: Clarify their point of view. They might consider the behavior as a feature, be unaware of the requirement, or see some specific detail that is not obvious to me. Dialogue often helps find the root of the problem.
6. Involve the Product Owner/Business Analyst: If after discussion with the developer no consensus is reached and I am confident there is a bug, I will involve the Product Owner or Business Analyst to determine priority and further actions. They can confirm that the behavior does not meet the requirements or, conversely, decide that it is acceptable.
7. Update the bug report: Enter all collected information, discussion results, and the decision made into the bug report.
8. Close the bug (if necessary): If, based on the decision of the Product Owner/Business Analyst or reaching consensus with the developer, it turns out that this is not a bug or the defect is considered acceptable, I will close the bug report with an appropriate comment.