Depends on the aspect. There is one aspect of modern car design which is objectively worse and unsafe: flatscreen controls in a center console.
Is it new? Yes. Is it modern? Yes. But there is no tactile feedback and requires the driver to take their eyes off the road to adjust a setting like thermostat or music.
So much so the EU is adjusting safety guidelines to require physical controls again.
I know people who are looking for used cars older than their current model if they need to get a new one because they have physical controls you can use without taking your eyes off the road.
So modern does not exactly equal better.
For UI design, what people usually refer to as “modern” is flat, information-sparse design. This works great on phones with limited screen space. You need information presented to you in in a linear way.
Desktops are not phones, and allows for more information density. I’m not saying you have to flood every pixel with info, but try to allow for more info without making it as sparse as a phone. Modern design can make a desktop less usable. (Look at how well macOS Tahoe is going.)
Laptops are an inbetween, and this can go either way depending on preference. But you can still use multiple monitors with a laptop, and may have a larger screen where you prefer more density.
A problem with “modern” design is precisely this lack of info. Having broad areas of open space and requiring scrolling or changing screens to get information can increase cognitive load.
Another example would be hamburger vs. pulldown menus. The former usually shifts the entire menu out of view to show submenus, which again, increases cognitive load. On a desktop using a nested pulldown menu doesn’t lose your place. Could these interfaces be improved? Certainly. But no reason to ditch desktop metaphors entirely when they work surprisingly well on a desktop.
Also check out this Drum Machine app and this Sudoku app. Despite being two very different things, they have a very similar look so at first glance you have to spend more time to figure out what’s going on. This is not as much an issue with a mobile device where generally only one app is on screen at a time, but is much more of an issue where you have multiple apps open at the same time.
Basically design is hard. There is no “Modern” filter in graphics apps that magically changes a whole interface. “Modern” isn’t necessarily better in a lot of use cases. Many time it’s just chasing trends, which may actually be a detriment to everyone involved like a flatscreen panel in a car.
So a better question might be, “What current problems does this new design solve?”