Description of problem:
According to the code of net-lib.sh and the manual of dracut.cmdline, the ip argument from the cmdline used for early networking setup may have several forms, including this one:
ip=<client-IP>:[<peer>]:<gateway-IP>:<netmask>:<client_hostname>:<interface>:{none|off|dhcp|on|any|dhcp6|auto6|ibft}[:[<dns1>][:<dns2>]]

The last columns are not parsed, so the DNS1 and DNS2 are not present in the generated ifcfg files (which are themselves used by the NetworkManager).

Version-Release number of selected component (if applicable):
# rpm -qf /usr/lib/dracut/modules.d/45ifcfg/write-ifcfg.sh 
dracut-network-049-10.git20190115.el8.x86_64

How reproducible:
echo "kernel_cmdline=ip=192.168.122.100::192.168.122.1:255.255.255.0::ens3:none:8.8.8.8" > /etc/dracut.conf.d/static_ip.conf
dracut -fv --regenerate-all

Actual results:
No DNS1 and DNS2 entries in /etc/sysconfig/network-scripts/ifcfg-*

Expected results:
DNS1 and DNS2 are present in the ifcfg file.

Additional info:
The code of write-ifcfg only iterates the nameserver arguments from the cmdline.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    i=1
    for ns in $(getargs nameserver); do
        echo "DNS${i}=\"${ns}\"" >> /tmp/ifcfg/ifcfg-$netif
        i=$((i+1))
    done
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~