That's what's nice about coarse-grained feature options like Rust's editions or Haskell's "languages", you can opt in to better default behavior and retain compatibility with libraries coded to older standards.

The "null vs null" problem is commonly described as a problem with the concept of "null" or optional values; I think of it as a problem with how the language represents "references", whether via pointers or some opaque higher-level concept. Hoare's billion-dollar mistake was disallowing references which are guaranteed to be non-null; i.e. ones that refer to a value which exists.