There we have a similar issue to https://gitlab.haskell.org/ghc/ghc/-/issues/21737 The problem is this: ```haskell -- W will contain the ints directly data T = T !(# Int, Int, ..., Int #) data W = W !T -- W2 will unbox W, since it assumes the unboxed tuple to be a single value and doesn't -- account for (# #) already being unboxed. data T2 = T2 !( Int, Int, Int) data W2 = W2 !T2 ``` When deciding if we should unpack `T` into `T2` we will see that `T` has just a single field (the unpacked tuple) so we unpack. However this ignores the fact that unboxed tuples are always "unpacked" increasing the size of `W` to an potentially arbitrary size.