CV shaft broken

My 16 year old bought a 06 Santa fe 2.7L Fwd 180xxx miles. He had ABS problems. Found the tone ring on the driver's cv shaft was broken and slipping out of place.
I replaced the shaft (autozone) Two weeks later he called "it made a clunk and now acts like it's in neutral" I looked it over. The new cv shaft fell out. Turns out it broke the tip off and retaining ring. Marked it down as a fluke and replaced it again.
Now three months later it did it again. What could be causing the shaft to break the retaining ring off like this?

Sometimes manufacturers will redesign parts...if it was not quite an exact fit it could break off.

It also could be a weak aftermarket part (hopefully under warranty!)

I would take the original if you by chance still have it, and try an OEM part.

Could your son be doing burnouts and causing axle problems?

That was my thought was just a bad quality. I do not have the original one. When I replaced it it did look the same side by side. Yes it's a lifetime warranty, and a easy job replacing it.

His driving was one of my thoughts too. However I would think aggressive driving would brake the shaft outside of the trans and not inside where it's splined together.