Not sure what’s going on but it says my number is not part of the leak, but I’ve checked myself and it is actually leaked. Just be aware that it may not be complete.
We can be pretty sure the results are legit but yes of course it could be running malicious code and stealing phone numbers. Check the raw data if you are worried[2].
[1] https://github.com/Fumaz/haveibeenfacebooked-api [2] https://archive.is/MZqak