Multiple in fact. D1 vs D2, Tango vs Phobos, mutable by default vs const by default (was minor, but allegedly lead to the existence of Rust), Adam D Ruppe leaving and forking the compiler (OpenD - might be useful to you depending on things), "let nazis code" (though DLF have not only backtracked on it but also set up some basic safety measures), etc. Can still recommend the language if you want a more C-style language and not OCaml with curly brackets, or if borrow checker is a dealbreaker for you in Rust.