In Delphi 11.2 (and all Unicode Delphi versions), the function ReceiveData uses WinApi Function HTTPQueryInfo, which calls the WideString variant HTTPQueryInfoW.
The 4th parameter of HTTPQueryInfoW “amount of written bytes” is the same as for HTTPQueryInfoA. Your code uses this Size to set Length of string, in Unicode Delphi of UnicodeString. Which results in partially random strings, with a lots of broken letters.
IndyComponents use {$IFDEF UNICODE} div 2{$ENDIF}) on same spot.
Example:
...
if (l_status >= 300) and (l_status <> HTTP_500_code) then begin
l_index := 0;
l_size := const_MaxStatusText;
SetLength(l_statusText, l_size);
if HTTPQueryInfo(aRequest, HTTP_QUERY_STATUS_TEXT, @l_statusText[1], l_size, l_index) then begin
SetLength(l_statusText, l_size {$IFDEF FIX_IT} div SizeOf(Char) {$ENDIF});
raise EROWinInetHttpException.CreateFmt('%s (%d)', [l_statusText, l_status], GetLastError);
end;
end;