agree with the others about the lint being the likely culprit for charging issues.
yet, in the flip side, you have to think about what you would want in the rumored iphone12 vs iPhone 11 series given you are facing other challenges with you iPhone 7. from what the rumors suggest, the 12 will have:
- time of flights sensor on rear
- 5G
- come in different sizes (5.4, 6.1, and 6.7")
- another camera upgrade? (to compete with Galaxy S20 ultra)
to me, none of these are that important with the exception that they actually are rumored to be removing the 5.8" model. i'd be fine with the 5.4" model, but i would want the telephoto lens that may only come on the 6.1" and 6.7" models if the rumors are right.
5G, IMHO, isn't ready for prime time, even though i live in the SF Bay Area and won't be for at least another couple of years. even then, i don't do anything heavy duty network need wise, so existing LTE is good enough and may be even better if people move over to 5G
i'm not in AR, so the first feature isn't relevant until someone shows me how it would be life changing to me. the only thing i would feel like i missed is if they introduced an optical zoom on the telephoto lens to follow Samsung.
but beyond that, i think the 11 series will be excellent phones to use for the next several years.