Earlier quoted context omitted.
That's an unweighted trailing average where the bulk of the increase came from earlier months. Instantaneous inflation in December 2022 annualizes to 2%.
"The index for all items less food and energy rose 0.3 percent in December, following a 0.2-percent increase in November. The shelter index continued to increase, rising 0.8 percent over the month." Food inflation increased over November. Shelter index increased at an annualized rate of nearly 10%. Sometimes, you have to dig deeper than the headline. Source: https://www.bls.gov/news.release/pdf/cpi.pdf
"Last month, inflation was 6.5%" is not correct by any reading of this data! Your link makes it clear that was inflation over the course of 2022, as I said in clunkier language. The graph on that same first page shows most of that inflation happened in the first 6 months of 2022.
The average of the last 6 months in that graph is 0.15, or ~1.8% annualized. That's an arbitrary cutoff (including July's 1.3 shoots up to 3.9% annualized!), but it seems clear we're on the right track. If the next 6 months look similar to the last 6, we will look back and say inflation was already under control before 2022 ended.