auto inf = std::numeric_limits<double>::infinity();
    auto neginf = -1 * inf;
    assert(inf != neginf);

    QVariant a(inf);
    QVariant b(neginf);
    assert(a != b);

The second assertion fails, but IMHO it shouldn't. It all gets down to qFuzzyCompare(), which returns true for this case.

There is a QTBUG-50036, that is somewhat similar and might have caused this issue.