The last Leafs-owned first-round pick of the Dubas era is Rasmus Sandin, who was drafted in 2018. The most recent first-round pick the Leafs acquired was from the Pittsburgh Penguins, which they used to select Rodion Amirov in 2020. The team's highest draft picks in 2021 and 2022 being in the second round.
Dubas has constantly been criticized as a GM that doesn't 'go all in' by the standards of hockey fans and media, but he sure doesn't mind trading high picks and then finding value beyond the first round on the draft floor. In case anyone has forgotten, the Leafs' top prospect, Matthew Knies, was selected 57th overall. Fraser Minten, drafted this past summer, also appears to be a quality prospect with a ton of upside. He was selected 38th overall.
To me, Dubas has done nothing but prove he is a GM that believes in his core and his roster. On paper, there's no reason for him not to believe in them aside from their unfortunate playoff track record. He's not a perfect GM by any means, but Dubas has always been willing to make tweaks where necessary, and if they didn't go as planned, he found something else and made the most of what he had during a stretch where the cap remained flat despite all of his original projections taking into account annual cap increases that never came.
Dubas gets a lot of flak, but for a guy who is criticized as much as he is for not making bold deadline moves, he has certainly made a lot of big time moves in the weeks leading up to the deadline. The question of where the postseason success has been in light of having spent all of these picks is another conversation for another time, but could be pre-emptively answered with a deep run this spring/summer.