The most sold vehicle in the USA are oversized pick-up …
I'd like to see the figures you're looking at. SUVs are usually counted as "light trucks", and manufacturers have killed off a lot of car lines and replaced them with SUVs.
More people are buying electric cars. Electric cars are heavier, and so are electric "light trucks". More electric cars on the road is going to push the average weight of vehicles on the roads upwards. Heavier cars take farther to stop and they aren't as nimble. Heavier vehicles are more likely to be involved in an accident, and accidents are going to be more severe.
The F-150 Lightning weighs 6,500 pounds (2,900 kg), over 35% more than the internal-combustion-engine (ICE) powered equivalent F-150, with most of the additional weight a result of the Lightning's 1,800 pounds (820 kg) battery. The F-150 Lightning was one of several electric vehicles cited by National Transportation Safety Board head Jennifer Homendy as being significantly heavier than ICE-powered models and thus raising the risk of other road users being killed or seriously injured in collisions, alongside products from other manufacturers such as General Motors and Volvo.
https://en.wikipedia.org/wiki/Ford_F-150_Lightning#Overview
US official warns of risks posed by heavy electric vehicles
The official, Jennifer Homendy, raised the issue in a speech in Washington to the Transportation Research Board. She noted, by way of example, that an electric GMC Hummer weighs about 9,000 pounds (4,000 kilograms), with a battery pack that alone is 2,900 pounds (1,300 kilograms) — roughly the entire weight of a typical Honda Civic.
It is complicated and a lot of people are ignorant.