Easy. More monument or championship victories. Van Aert is a fantastic and unique rider in many ways. His versaility is tremendous. He can sprint, time trial, ride cobbles, attack in short hills and ride long mountains like no one else in modern cycling history. And his performances in many races are convincing. Both GC in one-week races, single stages in stage races, time trialing and the tier 2 one-day races like GW, Amstel and Omloop. But he hasn't won or even sprinted for victory in a monument (or worlds/olympics) since he was beaten by VdP in the Ronde in 2020.
That makes 6 of the biggest one day races without a win or sprinting for the win. Given his amazing level in so many other races, that is certainly a bit disappointing. Last year one could argue that he spent too much energy on competing in about every race he started, and that his hampered his performance in the very biggest races, but I can't see that this is the case this season. So unless something happens in the coming weeks, I certainly expect him winning or being real close to a victory in RVV and/or PR.