Cracking bonnet protectors

[Ray_aus]

I have just noticed my third bonnet protector on my 2018 Everest cracking, the original factory protector flew off the car after only a few months ( I hand just removed and reinstalled to clean under it ) and subsequently two others aftermarket protectors I purchased also cracked.
I made sure that the screws weren’t over tighten and even used Loctite on the screws so that they were not to tight.
On my last bonnet protector I started from scratch, I removed all the clips and used the new ones that came with the protector.
The positioned of the screw holes were all central.
The plastic did not appear to be under any stress at all.
This last one only lasted less then a month and driven under 100km at city speeds.
I do have a rhino bull bar and just wondering if it’s deflecting air up and under and stressing it.
Any thoughts would be appreciated.