Okay, that first test on mine was maybe a dud. I just ran and got a more reasonable number:
sudo dd if=/dev/zero of=/home/pi/test bs=8k count=50k conv=fsync; sudo rm -f /home/pi/test
51200+0 records in
51200+0 records out
419430400 bytes (419 MB, 400 MiB) copied, 14.3804 s, 29.2 MB/s
Found the test and a table with good SD cards suggestions at microSD Card Benchmarks | Raspberry Pi Dramble