NASA (NOAA and GISS in particular) have made up their minds that Earth is warming. So if the data doesn't show warming, they manipulate it until it does.
I can't provide all the information (I didn't even chase it after the pattern became clear), but here are some basics:
1. We have data from the 1930s for continental USA, because people recorded temperatures.
2. It used to be, and NOAA agreed (but kept in wraps), that our "hottest years" were not hotter than 1930, or if hotter, only in 2nd and 3rd decimal places.
3. This was not comfortable for NASA, that 1930s were hotter than now or equally hot.
4. Somebody made up a theory of ocean temperatures. The data isn't really available, but some ships' logs did have temperature recordings. This is surface wind temperature, and doesn't say much about average ocean temperature.
6. The theory of ocean temperatures calculated average ocean temperatures from this sparse ships' logs data. And surprise, surprise, the ocean data made 1930's not so hot. Thereby allowing NASA freedom to say "hottest ever" and other headline stuff.
7. So when NASA says "hottest", they mean after "cleaning up" 1930's data.
8. Since 1998, there has been no warming, and even James Hansen admitted it.
9. Somebody was able to modify the data since 1998 in such a way that now the modified data shows warming. This modification was around 2015 - it took them 17 years to come up with a filter that turned all data into warming.
10. Until then, NASA scientist James Hansen admitted to the lack of warming and flat temperatures in a research paper, but never publicly announced it.
11. NASA supports filters that can turn random ("red noise") data into warming. This was evident in a case of Michael Mann, whose "red noise to warming" data was never contradicted by NASA.
12. The latest "turn to data" was actually a clever fraud, NASA _removed_ existing filters which took care of various data that was known to be bad and showed warming that didn't exist. In the theater of politics, where people don't understand details, it gave NASA yet another plausible deniability "We just removed the filter, we didn't add anything, honest!"
So given that the underlying theory of CO2 is wrong, and NASA has turned themselves into frauds, the "best fit" of the data says there is no warming, NASA is just lying as usual.
The Zarakhova theory appears correct from various indicators. I think even the "low science, low facts, low integrity" folks at WUWT have been able to show that the Earth has been cooling since 2017.