I downloaded QT 6.2.2, verified its checksum:

certutil -hashfile qt-everywhere-src-6.2.2.zip MD5

Building for Windows with MSVC2019

Configured QT for building in the system Command Prompt (but not in MSVC Developer Command Prompt) as follows:

CALL "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat" amd64
  
set "CMAKE_ROOT=E:\PFiles\cmake-3.21.3-windows-x86_64\bin"
set "NINJA_ROOT=E:\PFiles\ninja-win"
set "PERL_ROOT=E:\PFiles\Strawberry\perl\bin"
   
set PATH=%CMAKE_ROOT%;%PATH%
set PATH=%NINJA_ROOT%;%PATH%
set PATH=%PERL_ROOT%;%PATH%
set PATH=E:\PFiles\Python35;%PATH%
     
rem Check if the tools are in PATH
where perl.exe
where python.exe
where cmake.exe
where ninja.exe
 
set "MY_INSTALL_PATH=E:\Qt\Qt6.2.2\windows"
set CL=/MP
 
configure.bat -prefix %MY_INSTALL_PATH% -DQT_NO_EXCEPTIONS=1 -debug-and-release -force-debug-info -platform win32-msvc -opensource -confirm-license ^
-opengl es2 -I "C:\Program Files\OpenSSL\include" -L "C:\Program Files\OpenSSL\lib"

CMake did not work and there was a yellow triangle at the left side of MSVC2019 kit name:

I fixed this buy changing C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat with C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsx86_arm64.bat.

In QT 5.15 I declare a class with an invokable constructor:

class TestClass : public QObject
{
    Q_OBJECT

public:

    Q_INVOKABLE TestClass(QString val) {}
};

Q_DECLARE_METATYPE(TestClass*)

register its type:

qRegisterMetaType<TestClass*>();

I get close reason: ‘Invalid UTF-8 code encountered.’ (code=1007) with QWebSocket in the following scenario:

• I connect to Binance stream wss://stream.binance.com:9443/stream with QWebSocket::open.
• Successfully receive messages for some time period (a few hours).
• Binance disconnects me when its servers load increases (because I have low-priority API) and I get close reason code=1000 that indicates a normal closure.
• Try to reconnect multiple times by calling QWebSocket::open again, but Binance closes the connection with close reason ‘Invalid UTF-8 code encountered.’ (code=1007) that indicates that an endpoint is terminating the connection because it has received data within a message that was not consistent with the type of the message (e.g., non-UTF-8 [RFC3629] data within a text message).
• Restart the application manually and connect successfully.

The difficulty of reproducing the bug is that Binance disconnects me rarely (once a day, for example) and experimentation with disconnecting the network cable from my machine does not have this effect, after I connect the cable back, QWebSocker reconnects successfully. When I disconnect the network cable I get Error: ‘Unknown error’ (code=-1), Close reason: ” (code=1000).