This is a comment left during a code review.
Path: posthog/feature_flags.py
Line: 777-787

Comment:
**`fromisoformat` rejects space-separated timezone offsets on Python 3.10**

`datetime.fromisoformat` on Python 3.10 does not accept a space between the time and the UTC-offset (e.g. `"2022-04-05 12:34:12 +01:00"`), raising a `ValueError`. Python 3.11 expanded `fromisoformat` to accept most ISO 8601 forms, but since `requires-python = ">=3.10"`, any property value string in that format will fail on 3.10 where `dateutil.parser.parse` previously succeeded. The test `test_parse_datetime_matches_dateutil_for_supported_formats` itself includes this exact case, so it will only pass on 3.11+. A simple normalisation before calling `fromisoformat` would cover it:

```python
def parse_datetime(value: str) -> datetime.datetime:
    text = value.strip()
    if text.endswith("Z"):
        text = text[:-1] + "+00:00"
    elif text.upper().endswith(" UTC"):
        text = text[:-4] + "+00:00"
    elif re.fullmatch(r"\d{4}", text):
        now = datetime.datetime.now()
        return datetime.datetime(int(text), now.month, now.day)
    # Normalise "... +HH:MM" (space before offset) accepted by dateutil but not
    # by fromisoformat on Python < 3.11.
    text = re.sub(r" ([+-]\d{2}:\d{2})$", r"\1", text)
    return datetime.datetime.fromisoformat(text)
```

How can I resolve this? If you propose a fix, please make it concise.

---

This is a comment left during a code review.
Path: posthog/test/test_feature_flags.py
Line: 4582-4589

Comment:
**Prefer parameterised test**

Per the project's simplicity rules, parameterised tests are preferred. The loop over a tuple of strings is equivalent to a parameterised test but hides failures behind a single test name and stops on the first failure, making it harder to diagnose which format broke.

```python
@parameterized.expand([
    ("iso_date", "2022-05-01"),
    ("iso_datetime_Z", "2022-04-05T12:34:12Z"),
    ("iso_datetime_utc", "2022-04-05 12:34:12 UTC"),
    ("iso_datetime_offset", "2022-04-05 12:34:12 +01:00"),
])
def test_parse_datetime_matches_dateutil_for_supported_formats(self, _name, value):
    assert parse_datetime(value) == parser.parse(value)
```

How can I resolve this? If you propose a fix, please make it concise.