Yes, there are some weird things going on with COVID-19 infections in young people, but we need to keep in mind these are thankfully extremely, extremely rare. The articles you're providing links to amount to largely anecdotal evidence - a case here and a case there.

I'm not trying to be dismissive, but just want to point out that these are not things in my opinion we need to be afraid of. There are always going to be instances of people dying unfortunately early because of some weird thing, whether it's the brain-infecting amoebas or getting struck by lightning. Those are just, thankfully rare events.