downdetectorsdowndetector.com does not load the results as part of the HTML, nor does it do any API requests to retrieve the status. Instead, the obfuscated javascript code contains a `generateMockStatus()` function that has parts like `responseTimeMs: randomInt(...)` and a hardcoded `status: up` / `httpStatus: 200`. I didn't reverse-engineer the entire script, but based on it incorrectly showing downdetector.com as being up today, I'm pretty sure that downdetectorsdowndetector.com is just faking the results.
downdetectorsdowndetectorsdowndetector.com and downdetectorsdowndetectorsdowndetectorsdowndetector.com seem like they might be legit. One has the results in the HTML, the other fetches some JSON from a backend (`status4.php`).