QDateTime::fromString generating invalid data with DST days

When creating a QDateTime object using ::fromString if the date is in the daylight saving time change the object may not be valid (as isValid() sees or toString() fails).

To better understand I made a small example also attached (x.cpp).

#include <iostream>
#include <QtCore/QDateTime>

int main (int ac, char **av) {
    QString tmp("2008.10.19");
    QDateTime ts = QDateTime::fromString(tmp, "yyyy.MM.dd");
    std::cout << "Date: " << ts.toString("dd.MM.yyyy hh.mm").toStdString() << std::endl;
    std::cout << "From epoch (ms): " << ts.toMSecsSinceEpoch() << std::endl;
    std::cout << "Valid: " << ts.isValid() << std::endl;
}

If this code is called with a TZ='Brazil/East' it will output:

$ TZ='Brazil/East' ./x
Date: 
From epoch (ms): 1224385200000
Valid: 0

If called with a TZ='GMT' it will output:

$ TZ='GMT' ./x
Date: 19.10.2008 00.00
From epoch (ms): 1224374400000
Valid: 1

I don't know if this is expected behavior for this code, but it seems the QDateTime should generate a valid object since it didn't receive time values, only date (yyyy.MM.dd), also on both timezones the ms from epoch seems right.}}

I tested this on Ubuntu 18.04.1 LTS (Qt 5.9.5) and Gentoo (Qt 5.9.6).

Thanks!