How to fix:
file qtwebengine\src\core\network_delegate_qt.cpp
method NetworkDelegateQt::OnBeforeURLRequest

OLD CODE:

for (auto header = infoPrivate->extraHeaders.constBegin(); header != end; ++header)
request->SetExtraRequestHeaderByName(header.key().toStdString(), header.value().toStdString(), /* overwrite */ true);

NEW CODE:

for (auto header = infoPrivate->extraHeaders.constBegin(); header != end; ++header)

{ std::string h = header.key().toStdString(); if (base::LowerCaseEqualsASCII(h, "referer")) request->SetReferrer(header.value().toStdString()); else request->SetExtraRequestHeaderByName(h, header.value().toStdString(), /* overwrite */ true); }