Why is my charger making my phone do weird things?

Pretty vague question, but there's really not much to say or describe... This is a brand new iPhone 7 (since November), and every time I use a charger, no matter if it's third party or Apple certified, it makes my phone do weird stuff. I first began to notice the frequency of this has since mid 2017, or last year basically, when I still had my (cracked) iPhone 6.

Now, my iPhone 6 had been dropped in water, been cracked and dropped multiple times, has had the battery heat up to the point where I couldn't hold it without hurting my hand, so I can understand in that aspect. But this is a brand new iPhone... Let me clarify first, when I say 'weird stuff', I mean I'm charging my phone and trying to go onto Instagram, but despite me pressing right on the button to open the app, it'll switch to the next screen and/or open random apps by itself. Or if it's on an app, it'll type by itself and start sliding up and down. And this doesn't happen when I'm charging my phone in my car! It only happens when I'm charging through an outlet (so far, anyway..)

I don't know what's going on at this point. I don't know if something's been off about Apple's manufacturing/assembly, or what, but it's really getting annoying. I can't use my phone while it's charging because I'm afraid it'll randomly call someone, send random gibberish through whatsapp or imessage, delete important things, etc.

If anyone can offer any advice or has had a similar experience, let me know.