My understanding is that this assignment is unnecessary and can be
removed.
https://bugs.gentoo.org/981337
https://github.com/pygame/pygame/issues/4716#issuecomment-6104711463
--- a/src_c/cython/pygame/_sprite.pyx
+++ b/src_c/cython/pygame/_sprite.pyx
@@ -147,3 +147,2 @@
     def __cinit__(self):
-        self.__dict__ = {}
         self.__g = set() # The groups the sprite is in