As mentioned in the stgdict.c comment, this relates back to #22273 and #29565. The passing of arrays/structs is fragile, to use a euphemism. The ctypes behavior conforms to the x64 Linux ABI and x64 libffi, even the comment from #22273,

"Structs that are larger than 32 bytes get copied to the stack (see classify_argument in ffi64.c), so we don't have to worry about classifying their elements for register passing. Thus if a new field is added for this in StgDictObject, then PyCArrayType_new should only allocate it for array types that are 32 bytes or less. Using it for larger array types would serve no point.

And now we're at the crux of the problem.  I don't know what Ronald and others recommend.  ctypes is choosing x64 behavior to define an inherently target-dependent and ABI-dependent design decisions.  The real solution requires that _ctypes/stgdict.c incorporate target-specific logic, but it's not clear that the Python community wants to go down that path.