Nintendo Switch Joy-Cons no longer shine?

My Joy-Cons can't be individually connected wirelessly to my switch. If I want to use a Joy-Con as a single controller, I can't. And neither of them shines anymore. But if I use both Joy-Cons together wirelessly, it works and when docked they also work without problems. Only if I want to use a single Joy-Con as a controller, that doesn't work. That means I can no longer use the Joy-Cons for two people.

Can someone help me? They can't be unloaded. I would like to be able to play in pairs again.

Actually, for the first time hearing about such a problem, you can write to Nintendo Support