YouTube Buttons Overlay even when the app is closed

Hi everyone! I hope you’ll understand what I’ll write even if I’m Italian.

I’ve noticed that when I open other apps than YouTube on my iPhone 12 Pro Max there is the buttons overlay of YouTube even if the app is closed.

i’ll attach a photo I’ve taken yesterday.

I have tried to delete the app and download it again, but this can not fix it. Maybe I have to contact YouTube but maybe the problem is on my phone?

I hope someone can help me.

thank you so much.