Improved upper bounds on the list chromatic number of $K_t$-minor-free graphs

It remains open whether every $K_t$-minor-free graph is $O(t)$-choosable. Postle proved that every $K_t$-minor-free graph has choice number $O(t(\log\log t)^6)$. At the end of an earlier version of a paper establishing an $O(t\log\log t)$ bound on the chromatic number of $K_t$-minor-free graphs, Del