SST anomaly maps are in respect to a certain period which is generally from 1960-1990 which was a cool period. That's called smoke and mirrors for the uninformed and easily duped.
That's irrelevant right now. The current anomaly maps show large cool areas attributable to El Nino. There are, of course, currently related meteorological effects happening, too. When La Nina fades, the surface waters will warm up. Whether that's normal or higher than the base period temperatures, the oceans won't look nearly so cold then, because the surface waters will be considerably warmer.