Fix rig. Plush toy (Bloody Bunny)

Hello there!!
Let someone explain to me, please. I want it when he moved his ear only so that the lower part does not transform. I do not want to do it in shape keys.


Well, I don’t know if you used automatic bone weights, but as you can see, there is some influence of that bone on the head part of the mesh as there are colors other than blue when you go into Weight Paint mode. Are you familiar with how weight painting works?

I do not get it a bit, and yes, I took automatic weights. Only after setting the way I moved the first bone was half the head moving. I had to delete it. I did something yesterday, but that’s not it.