Even-arity complete full tree local antimagic chromatic number conjecture

Let $T$ be a complete full $t$-ary tree, meaning a rooted tree in which every nonleaf has exactly $t$ children and all leaves have the same depth. Let $l$ be the number of leaves and let $\chi_{la}(T)$ be the local antimagic chromatic number. Even-arity complete full tree conjecture. For every even integer $t\geq2$,

$$\chi_{la}(T)=l+1.$$

The paper explicitly states this conjecture as open; it would sharpen the established upper bound $\chi_{la}(T)\leq l+2$, while the equality is proved in the paper for odd $t$.