Spinoza was the generation after Descartes. Their lives overlapped. The Cartesian god is also nature.

As wikipedia says " God follows a similar structure as Descartes’ ontological argument.".

But Spinoza does not have Descartes' understanding of cognition. Spinoza's 'proof of God' is entirely circular. Descartes asserts that there is a perfection of God (i.e., nature -- everything outside of your mind) which the human mind cannot inherently completely come to know, but that science reveals some, but never all, of that perfection. We now know this is true and why.

There were in fact may philosophers of that day that asserted that God is Nature. The Inquisition killed many of them.

Descartes according to the historians seems to have saved himself by declaring "Nature is God, and God does not lie." It was hard for inquisitors to suggest that God does lie. And it was good for Descartes' science that forever could then discover new true things about nature through the methods of science (empirical observation and replication, along with mathematical deduction). The ultimate result, after killing a lot of natural philosophers, was that the (Catholic) Church embraced science.

Spinoza was among the many 'natural philosophers' that are responsble for the enlightenment and age of reason. His variant on Descartes' view is not as logically sound as Descartes'. Descartes, correctly, is seen as the father of all this. The Frenchman Descartes died in 1650 (54 yrs old), Dutch Spinoza in 1677 (44 yrs old). Spinoza was 18 when Descartes died. Descartes was productive until he died of what seems like a cold in Sweden, hosted by the Queen.

The term Pantheism was coined in 1697, well into the age of enlightenment. It seems to be descriptive of any of the many variants on Descartes' original arguments that developed among the many argumentative variants on natural philosophy and enlightened religion. https://en.wikipedia.org/wiki/Pantheism

Some people seem to think Pantheism existed before Descartes, but not as such. The idea that God is nature and nature is God has existed for thousands of years. Various other forms of Pantheism also existed but not as such. There is no organized religion called Pantheism. It is more like an artificial interpretation of God that has instances that have existed along with many other interpretations of God for a long long time.

Both Descartes and Spinoza rejected an anthropomorphized "God". Descartes expressly said that man was part of nature that the brain reveals and can be studied for his perfections as a subject of empirical science. As such, I have argued Descartes is also the true father of Cognitive Science. Not so much Spinoza, who really just assumed that reality exists outside of the human mind. As Descartes uniquely said "I think therefore I am." (Descartes proof of God is part of this -- the thinking part that can see the perfections in reality/nature/God but never know all of them.)

We now know Descartes was right. It is fundamental to how animal brains cognitively compute. Think, "perceive and enact causation" by empirical replication and deduction.

https://medium.com/liecatcher/how-your-brain-computes-41ebe7428ff9