Could this be damaging my iphone chargers?

I have noticed that everytime I get a charger it worka fine until my brother used it. My brother has an iphone 5c like me but his phone has water damage. He still tries to charge it. Everytime he uses my charger my charger starts charging then uncharging. Is his phone damaging my charger or could it be something else?

It could be his phone. But some off brand cables can do that.

It's remotely possible. He should replace his phone.