When you're slowing down with growth spurts and things like that, you start eating less. It happened to me. I would be eating and eating all the time, then suddenly I wouldn't get hungry.
Less social could just be whatever environment you're in or you just need time to recharge. I'm an ambivert, so I can be really outgoing for a long time, but then I need awhile to recharge. Sometimes even up to one or two weeks.
Sleeping more is because in puberty your biological clock goes all wonky. That's why teenagers generally go to bed late and sleep in for a long time.
Everyone's restless during quarantine. There's nothing to do, and we desperately want to do something.
I know my muscles have weakened. I've always been physically strong. When I was five we were building a brick wall around the back garden with some of my parent's friends and I was lifting just as much as the men.
Then when I was about 11 I started staying inside more and doing things that don't keep your muscles going strong.
And during quarantine you're definitely not doing all that stuff. It's like a use them or loose them kind of thing.
So there's logical reasoning behind this that has nothing to do with death, and you shouldn't wish that you should die.