Why is iperf3 data transfer slower than scp?

I have been measuring the throughput between two hosts connected via a fiber channel. The OS is CentOS 7.9.2009 and iperf3 version is 3.1.7 (RPM). One of the tests was the measurement of transfer rates when the transferred data gets written to file. This is relevant because our application is write heavy. The server was started by running:

$ [server] iperf3 -s -F zero.img -i 30

The client by:

$ [client] iperf3 -c server -F zero.img -i 30 -p 5201 -n 95G

A large file used in the transfers was created by doing:

$ [client] dd if=/dev/zero of=zero.img count=100000 bs=1000kB

dstat was using to monitor system resources:

$ [server] dstat -t -m -s -d -c -l -n 60 10

iperf3 transferred the data at just about 10 MB/s.

While scp was way faster (over 130 MB/s).

Could anyone please suggest what could be the reason?