So that is mean that every time we will see a huge movement of bitcoin to a self custody wallet will automatically be a good news and positive trend?

There could be many reasons why someone or some entity will do that and it could be some exchanges or even online crypto based casinos doing that every month or whatever they feel they have to move it to make it safe.

That's why it doesn't make sense to look at this data or even follow some twitter account that monitor this kind of huge move in the market.