The speed limit on that road is actually 35mph, so FSD is doing the correct thing.
The map displays the incorrect speed limit, which is a defect due to school zone. My Tesla displays the incorrect speed limit in similar situations.
1/ The image was from a $TSLA "driverless" robotaxi in Austin, TX on Sunday. Notice anything? The car is traveling 35 mph when it knows the speed limit is 20 mph. This is indicative of the car being remotely driven by a human, not a computer. #robotaxi_fraud! Busted! @Tesla