I looked at the file name but not the document title (specifically because I was wondering if this is 3.1). Good spot.

edit: they just removed the reference to "3.1" from the pdf

I think this is 3.1 (3.0 Pro with the RL improv of 3.0 Flash). But they probably decided to market it as Deep Think because why not charge more for it.

	▲	WarmWash 4 hours ago \| parent [-]
		The Deep Think moniker is for parallel compute models though, not long CoT like pro models. It's possible though that deep think 3 is running 3.1 models under the hood.