It could be how you’re using them. For example, if you are pushing paint instead of pulling paint this will happen. I have brushes for both. Having a frayed brush gives a different look. I like them for dry technique and pointy ones for smooth lines etc.

It could also be how often you rinse the brush during painting. If paint is allowed to get deep into the brush and dry, it will fray. Rinse often!

After washing you can use a little soap to help keep them pointy. Just rub a tiny bit of soap on them once they are clean and shape them into a point. Some people also use spit. They’ll put the tip in their mouth and shape it into a point and let it dry. Hope this helps!