Could my phone screen be damaged?

There's a tiny rainbow colored vertical line near the center of my screen. Could my phone's LCD panel be a little damaged? I've dropped it a few times but it's in a case. It's an iPhone 7.

Can't comment on YouTube App?

So I have an iPhone and I comment a lot on the YouTube app I'm trying to comment on a video right now but it'a saying Error The operation couldn't be completed. (com.google.HTTPStatus error 503.) what should I do?

What's up with my Snapchat audio?

Whenever I record and talk or whatever, no one can hear it on my snaps. The only time it works is if I put on my earbuds, only then could people actually here me, music, etc.
Why is it like this? I want to be able to lip-sync to music on my snaps and act boujee:*(
I have an Iphone 6+

Added (1). Thanks Rhea, I actually did have one small incident with water getting on my phone… I did re-download and update the application so it could be water damage but it only happens on SC… Maybe I should go to a phone shop just in case there's water damage?

Should i buy the iphone x or the note 8?

I have been using an iphone 5 for almost 5 years and i'm upgrading this year because of college. I use my phone mostly for youtube and reddit and occasionally video games. And i was wondering which phone would be more suitable for me. Some people warned me from android because it becomes laggy after some months, is this true?

Can I create an iPhone hotspot when my iPhone is connected to wi-fi?

I have the problem that my computer only accepts an ETHERNET cable for internet. I was wondering if I could create a hotspot on my iPhone to then pass it on by USB to my computer. The issue is, I can't use 3G or mobile data, so I wanted to ask if there's a way to create a hotspot while your iPhone is connected to wi-fi (no jailbreak please).