If they got this number wrong by 60% for all these years and just noticed, why should I trust anything else about all of their different, conflicting climate models?
"However, these estimates all use the same imperfect ocean dataset and share additional uncertainties resulting from sparse coverage, especially before 2007"
You'll note here the methodology isn't the issue, but rather the dataset. They've improved the dataset.
> why should I trust anything else
Well, technically, you shouldn't. You can look at the data and review it yourself. The problem is, you aren't probably an expert in the field. Which means at some level, you've already put your trust in the experts at some level.
Furthermore, to double down on the "they didn't get it wrong" comment:
"Our result - which relies on high-precision O2 measurements dating back to 1991 - suggests that ocean warming is at the high end of previous estimates."
You'll note here that this they concluded the actual warming was still within the previous estimates. And considering estimates are just that, this further backs up their claim.