The domain of the function is from -128 to 128. The unexpected behavior of the function is observed in the intervals between -128 and -50, and between 50 and 128, where the function returns constant values different from the rest of the domain.

[CODE]:
```python
def f(x):
    if -128 <= x <= -50:
        return 0.8
    elif 50 <= x <= 128:
        return -8.6
    else:
        return 0.8
```

Please keep in mind that this description and code approximation are based on the limited set of inputs that were provided. It may be helpful to test the function on more values to confirm the accuracy of the description.