Sumner's conjecture for oriented trees

Let $T$ be an oriented tree, let $n=|V(T)|$ be its order, and let $\operatorname{unvd}(T)$ denote its unavoidability.

Sumner's conjecture. Every oriented tree of order $n>1$ is $(2n-2)$-unavoidable; equivalently,

$$\operatorname{unvd}(T)\leqslant 2n-2.$$

This is a celebrated conjecture about tournaments and oriented trees. The source does not state a resolution, so its status remains open.