It's a real problem across almost all forms of motorsports that are based on factory vehicles or even just factory bodies- for a few decades now, the average production car has been moving farther and farther away from making a suitable race car.
You could probably really trace it all the way back to when cars started shifting from body-on-frame to unibody construction. But that wasn't too bad to work with. The big changes started in the 80s when a majority of passenger cars shifted to front wheel drive with transverse engine and transaxle. At that point, building a race car out of these starting with an actual factory vehicle was no longer really an option unless you were in some niche front wheel drive/small displacement class (or did some SERIOUS reengineering to convert a front wheel drive car to rear wheel drive).
Motorsports that just needed to use a factory looking body on a purpose built chassis could still make it work, even if it was a little weird. So we got NASCAR Luminas, pro stock Berettas, etc.
After a few more decades of getting by that way, the body styles themselves shifted and we ended up where we are today- not only are there almost no vehicles suited to being traditional race cars in terms of drivetrain, there are hardly even any BODIES suitable for a race car anymore!
It's hard to know where to go from here. In NASCAR, GM has had to simply make up a 2026 Camaro because they don't have any production models to use. Do more companies/motorsports go that route- just basically make up car-like concept bodies? Will everything need to go to retro bodies? Or do we bite the bullet and start using crossover SUV bodies (blech!) for race cars? It's a real problem. Never mind the fact that most things built off a factory car (except for some muscle/pony cars) has not had a new suitable vehicle built in 40 years- there are only so many of them around. The Crown Vic was probably the last interesting option there, but now idiots have decided that it's fun to "race" them in glorified demolition derbies on a circle track so we'll burn through the supply of those in no time as well.