On that scene..
The scene itself is cute. A little boy singing some shit 80ies song for a girl. I get it.
The problem is the wider context.
The first season took its theme of being an early 80ies themed horror show and its characters seriously.
In the second season it started to feel self aware of its 80ies nostalgia thing, and played around with these tropes.
In the third season they went on full retard with this and just did it for the sake of pandering for the audience, and the moment where the dam breaks and it's completely getting into fulltard territory is that neverending story song scene.
It's just done for nothing else than people can say 'oh how cute and 80ies is this'.
It's the moment where the series jumped the shark.
There is no essence, it doesn't make any sense, and it's just there for effect.
It's like the story isn't important anymore and the series' main thing is nostalgia pandering without any meaningful base to it.