struct A {}

impl A {
    pub async fn get_simple(&self, _key: &[u8]) -> Option<impl AsRef<[u8]> + '_> {
        Some(Vec::new())
    }

    pub async fn get<'a>(&'a self, key: impl AsRef<[u8]>) -> Option<impl AsRef<[u8]> + 'a> {
        self.get_simple(key.as_ref()).await
    }
}

struct B(A);

impl B {
    pub async fn get<'a>(&'a self, key: &'a [u8]) -> Option<impl AsRef<[u8]> + 'a> {
        // This works
        //self.0.get_simple(key).await
        // This doesn't. Why???
         self.0.get(key).await
    }
}