I'd argue that Trump's mishandling of COVID, specifically the discontinuation of the Obama anti-pandemic procedures/policies, the endless attempts to downplay the disease, and discourage efforts to limit and contain the spread, peddling of misinformation and mistrust towards the medical and scientific community attempting to develop ways to stem the pandemic... directly influencing the leaders nationwide and worldwide who followed his example... and all the resultant needless deaths it caused, not just in the US, but globally... was worse than the Iraq invasion.
EDIT: I'll add that another reason it was worse, was because of his motives. The reason Trump mishandled COVID so badly, was because he was completely incompetent and all he cared about, was that taking it seriously might make him look bad politically, ie damage his chances of re-election. So he fostered a global pandemic that killed millions of people and caused all sorts of additional damage... economic, educational, psychological, etc., just because he didn't want to take the political hit. At least Baby Bush was motivated by a desire to secure the sources of oil to improve the US economy, enrich US corporations and allies and strengthen the US status as a global hegemon... certainly not necessarily a non-evil or noble goal, but it was at minimum, about something besides just personal benefit/aggrandizement.