This is a combination of three patches:

1. In generate_pyi.py, avoid writing to immutable typing.TypeVar.__repr__.
2. Backport PySide6 fix https://codereview.qt-project.org/c/pyside/pyside-setup/+/506424
3. Backport PySide6 fix https://codereview.qt-project.org/c/pyside/pyside-setup/+/506930

diff -ur python3-pyside2-5.15.5.orig/sources/pyside2/libpyside/pysideproperty.cpp python3-pyside2-5.15.5/sources/pyside2/libpyside/pysideproperty.cpp
--- python3-pyside2-5.15.5.orig/sources/pyside2/libpyside/pysideproperty.cpp	2023-09-27 21:52:01.389249419 -0400
+++ python3-pyside2-5.15.5/sources/pyside2/libpyside/pysideproperty.cpp	2023-09-27 21:57:06.265042322 -0400
@@ -46,6 +46,7 @@
 
 #include <shiboken.h>
 #include <signature.h>
+#include <basewrapper.h>
 
 using namespace Shiboken;
 
@@ -444,7 +445,13 @@
 static PyObject *getFromType(PyTypeObject *type, PyObject *name)
 {
     PyObject *attr = nullptr;
-    attr = PyDict_GetItem(type->tp_dict, name);
+
+    {
+        Shiboken::Type::TypeDict tpDict(type);
+        Q_ASSERT(tpDict);
+        attr = PyDict_GetItem(tpDict, name);
+    }
+
     if (!attr) {
         PyObject *bases = type->tp_bases;
         int size = PyTuple_GET_SIZE(bases);
diff -ur python3-pyside2-5.15.5.orig/sources/pyside2/libpyside/pysidesignal.cpp python3-pyside2-5.15.5/sources/pyside2/libpyside/pysidesignal.cpp
--- python3-pyside2-5.15.5.orig/sources/pyside2/libpyside/pysidesignal.cpp	2023-09-27 21:52:01.387249407 -0400
+++ python3-pyside2-5.15.5/sources/pyside2/libpyside/pysidesignal.cpp	2023-09-27 21:58:42.799610013 -0400
@@ -49,6 +49,7 @@
 #include <QtCore/QMetaMethod>
 #include <QtCore/QMetaObject>
 #include <signature.h>
+#include <basewrapper.h>
 
 #include <algorithm>
 #include <utility>
@@ -670,7 +671,10 @@
     PyObject *value;
     PyObject *key;
 
-    while (PyDict_Next(objType->tp_dict, &pos, &key, &value)) {
+    Shiboken::Type::TypeDict tpDict(objType);
+    Q_ASSERT(tpDict);
+
+    while (PyDict_Next(tpDict, &pos, &key, &value)) {
         if (PyObject_TypeCheck(value, PySideSignalTypeF())) {
             Shiboken::AutoDecRef signalInstance(reinterpret_cast<PyObject *>(PyObject_New(PySideSignalInstance, PySideSignalInstanceTypeF())));
             instanceInitialize(signalInstance.cast<PySideSignalInstance *>(), key, reinterpret_cast<PySideSignal *>(value), source, 0);
diff -ur python3-pyside2-5.15.5.orig/sources/shiboken2/libshiboken/basewrapper.cpp python3-pyside2-5.15.5/sources/shiboken2/libshiboken/basewrapper.cpp
--- python3-pyside2-5.15.5.orig/sources/shiboken2/libshiboken/basewrapper.cpp	2023-09-27 21:52:01.414249566 -0400
+++ python3-pyside2-5.15.5/sources/shiboken2/libshiboken/basewrapper.cpp	2023-09-27 21:55:00.575303169 -0400
@@ -1969,3 +1969,23 @@
 } // namespace Object
 
 } // namespace Shiboken
+
+namespace Shiboken::Type
+{
+
+TypeDict::TypeDict(PyTypeObject *t) noexcept :
+    m_pyObj(t->tp_dict)
+{
+    if (m_pyObj == nullptr) {
+        m_pyObj = PyObject_GenericGetDict(reinterpret_cast<PyObject *>(t), nullptr);
+        m_owned = true;
+    }
+}
+
+TypeDict::~TypeDict()
+{
+    if (m_owned)
+        Py_DECREF(m_pyObj);
+}
+
+} // namespace Shiboken::Type
diff -ur python3-pyside2-5.15.5.orig/sources/shiboken2/libshiboken/basewrapper.h python3-pyside2-5.15.5/sources/shiboken2/libshiboken/basewrapper.h
--- python3-pyside2-5.15.5.orig/sources/shiboken2/libshiboken/basewrapper.h	2023-09-27 21:52:01.416249578 -0400
+++ python3-pyside2-5.15.5/sources/shiboken2/libshiboken/basewrapper.h	2023-09-27 21:54:17.907052245 -0400
@@ -486,4 +486,33 @@
 
 } // namespace Shiboken
 
+namespace Shiboken::Type
+{
+
+/// TypeDict holds the tp_dict of a type. As of Python 3.12, tp_dict is nullptr,
+/// so, PyObject_GenericGetDict() needs to be used and the reference managed.
+/// FIXME: Replace by AutoDecRef when Python 3.12 is the minimum supported.
+class LIBSHIBOKEN_API TypeDict
+{
+public:
+    TypeDict(const TypeDict &) = delete;
+    TypeDict(TypeDict &&) = delete;
+    TypeDict &operator=(const TypeDict &) = delete;
+    TypeDict &operator=(TypeDict &&) = delete;
+
+    explicit TypeDict(PyTypeObject *t) noexcept;
+    ~TypeDict();
+
+    inline PyObject *object() { return m_pyObj; }
+    inline operator PyObject *() { return m_pyObj; }
+    inline operator bool() const { return m_pyObj != nullptr; }
+    inline PyObject *operator->() { return m_pyObj; }
+
+private:
+    PyObject *m_pyObj;
+    bool m_owned = false;
+};
+
+} // namespace Shiboken::Type
+
 #endif // BASEWRAPPER_H
diff -ur python3-pyside2-5.15.5.orig/sources/shiboken2/libshiboken/signature/signature_helper.cpp python3-pyside2-5.15.5/sources/shiboken2/libshiboken/signature/signature_helper.cpp
--- python3-pyside2-5.15.5.orig/sources/shiboken2/libshiboken/signature/signature_helper.cpp	2023-09-27 21:52:01.417249584 -0400
+++ python3-pyside2-5.15.5/sources/shiboken2/libshiboken/signature/signature_helper.cpp	2023-09-27 22:00:12.347136628 -0400
@@ -50,6 +50,7 @@
 #include "sbkstring.h"
 #include "sbkstaticstrings.h"
 #include "sbkstaticstrings_p.h"
+#include "basewrapper.h"
 
 #include "signature_p.h"
 
@@ -105,7 +106,8 @@
      */
     assert(PyType_Check(type));
     PyType_Ready(type);
-    PyObject *dict = type->tp_dict;
+    Shiboken::Type::TypeDict dict(type);
+    assert(dict);
     for (; gsp->name != nullptr; gsp++) {
         PyObject *have_descr = PyDict_GetItemString(dict, gsp->name);
         if (have_descr != nullptr) {
--- python3-pyside2-5.15.5.orig/sources/pyside2/PySide2/support/generate_pyi.py.orig	2023-09-27 22:20:58.761497093 -0400
+++ python3-pyside2-5.15.5/sources/pyside2/PySide2/support/generate_pyi.py	2023-09-27 22:21:27.701667008 -0400
@@ -113,9 +113,6 @@
                     prefix = '~'
                 return prefix + self.__name__
         """
-        def _typevar__repr__(self):
-            return "typing." + self.__name__
-        typing.TypeVar.__repr__ = _typevar__repr__
 
         # Adding a pattern to substitute "Union[T, NoneType]" by "Optional[T]"
         # I tried hard to replace typing.Optional by a simple override, but