Remember that Arxiv is not a scientific journal. Anyone* can post whatever they want there. It’s full of proofs of P=NP and zero-point energy designs and whatnot.
Looking at their argument itself, they seem to be saying that increased temperatures can be attributed to increased cloud cover rather than anthropogenic CO2. I don’t necessarily have the expertise to say whether that holds water, but even if so, it begs the question- what’s driving the increase in cloud cover? The correlation with anthropogenic CO2 remains unaccounted for.
(*Anyone associated with a college or university, or who has such a person vouch for them, or etc. It’s a bit like getting an invitation to gmail back when it was “in beta.”)