We can't draw conclusions from that study because it's been retracted on the basis that data has been faked.
On the other hand there are other similar studies that reach similar conclusions, and specifically try to control for aerodynamics e.g. [1] which says
> The weak positive relationship between vehicle registration year and splat rate suggests that newer vehicles are more efficient at sampling insects than older vehicles.
i.e. they saw more insects on newer cars compared to older ones in the same time period.
In general ecology studies aren't like lab physics, you can't control every possible confounding variable; the systems are too complicated and studies ex-situ have their own limitations. But refusing to engage with the data we do have because it's not perfect isn't going to help you make better decisions, and doesn't represent some moral high ground.
[1] https://cdn.buglife.org.uk/2022/05/Bugs-Matter-2021-National...