Translated by google:
>>Activation Lock Removal
Malicious actors forced me to link their iCloud account to the iPhone and triggered Activation Lock. I provided Apple with proof of purchase and a request to remove the Activation Lock, but received the following response:
"We were unable to fulfill your request to remove Activation Lock for this device.
No further review of any additional requests or documents regarding this device will be conducted."
What should I do?<<
Sorry, but if the official Apple Support decides, that it is not possible to remove the Activation Lock, there is nothing to can do about that.
Maybe your device did not meet all requirements needed:
...
You must be the owner of the device.
Apple may require proof of purchase. Proof of ownership must include the product serial number, IMEI or MEID.
Your data on the device will be erased.
If Apple unlocks Activation Lock on your device, all files and data stored on your device will be permanently erased. Please note, restoring your device from a local backup will re-enable Activation Lock.
We can’t unlock a managed device.
If your device is owned by a business or educational institution, please contact your IT department or manager. We also do not accept bulk requests.
Your device must not be in Lost Mode.
...
copied from: Additional Support - Activation Lock