I successfully completed the LFCS Tuesday. I got my results last night. I earned the credential initially in 2017 under the previous domains. While challenging then, it is certainly more difficult now and more indicative of a senior sysadmin. It is a great credential for a linux professional that has a certification requirement.
Advice for prepping for it:
Lots of practice on all domains at the shell. Make use of the LA playground or your homelab.
Firewall and packet filtering = know iptables. No firewalld here.
In addition to the Linux Academy LFCS course, do the Linux Networking and Troubleshooting course with Michael.
If you are unfamiliar with containers go through Essential Container Concepts with Ell.
If you are weak in the shell, grab the bash scripting, working at the command line, and the regular expressions course. You will not pass this test with negligible shell skills. In this context shell = bash.
The materials here are great and a great value. They are not sufficient by themselves and practice/experience is a must.