readyRead() is not emitted recursively; if you reenter the event loop or call waitForReadyRead() inside a slot connected to the readyRead() signal, the signal will not be reemitted (although waitForReadyRead() may still return true).
https://doc.qt.io/qt-5/qiodevice.html#readyReadПока ты не выйдешь из слота, сигналов тебе не поступит.