> "These restrictions were put in place because this content violates Google Drive's Phishing policy."
> There is no indication of why the file was flagged.
Isn't your answer in the warning (albeit lacking some specificity)? If you have a bunch of URLs in there and admit not knowing about their legitimacy, it seems reasonable that at least one of them matches a database of known phishing URLs. Isn't it also reasonable to expect (and in many cases want) a company hosting publicly-shared files to notify users when content matches some heuristics for unsafe content, especially given the prevalence of phishing attempts?
That said, there may still be a case to argue that the review process, heuristic, lack of transparency, and other implementation details are flawed. But I don't have a problem with them posting a warning message on content that looks suspicious.
Complete removal, on the other hand (as in the case of OP) is another story, especially given Google's laughable process (or lack thereof) for appealing such cases.