Serial.wz

import serial_wz as wz
data = "id": 101, "name": "sensor_01", "values": [1.2, 3.4, 5.6]
packed = wz.encode(data)
print(f"Encoded size: len(packed) bytes")
decoded = wz.decode(packed)
print(decoded)  # 'id': 101, 'name': 'sensor_01', 'values': [1.2, 3.4, 5.6]

strings serial.wz (Linux) or findstr /? with careful usage.

Look for readable text:

On Windows:
openfiles /local / handle.exe from Sysinternals
On Linux:
lsof | grep serial.wz

Which application is accessing the file? That program likely created it.