Well, yes.
Everything from feature requests, to PEP 541 requests are on the tracker. Anything that’s not an immediate security concern as per the security policy, goes there. w.r.t. flagging packages, that’s a feature request that’s a part of User support ticket system · Issue #3231 · pypi/warehouse · GitHub.
Also yes. I don’t think anyone minds it but they’ll likely get a quicker response on the issue tracker.