Verify this security report's claim without breaking things

I received this security report: [paste the report]. Verify whether the claim is real on [app URL] — safely. Ground rules: read-only verification only. Do not exfiltrate real user data, do not modify or delete anything, and do not run the attack at scale. Use a test account [test account details, or tell me to create one] where possible. Reproduce just enough to confirm or refute the claim — for example, whether the endpoint really returns another user's data, whether the parameter is actually injectable, or whether the page is reachable without auth. Write up: the claim in one sentence, what you did step by step, screenshots and request/response evidence, your verdict (confirmed, not reproducible, or partially true), severity in plain terms, and the fix you would prioritize. If anything looks too risky to test, stop and flag it instead.