No, no, no. Spinoza also proved God to be a fact, and as such you are misreading Spinoza.

The only option to recognize God as a fact is when indeed we declare God to be in/with everything there is. As such, we have a direct understanding of God in the abstract.

And that is different from declaring God to be the same as everything.

Space is infinite. This can be declared a fact (unless you have a different opinion).

The point is that God cannot be infinite, and this be seen as a fact. Anything infinite is not an entity, so there can then not be a factual God.

You have to see God as a fact to understand Spinoza's words correctly.

So, the difference is incredibly small, but you have to read Spinoza's words correctly. Do not miss the fine point. We can declare God to be the same as everything there is, but... there is then still something extra: Space.

Spinoza was very smart. Don't interpret his words the way you like to read it.