From what I can tell, 20230625 is the latest tagged release of of the linux-firmware repo: https://git.kernel.org/pub/scm/linux/kernel/git/firmware/lin...

Either way, as noted elsewhere in the comments, only the Rome CPU series has received updated microcode with fixes. All other Zen 2 users need the fix that was released as part of Linux 6.4.6: https://lwn.net/Articles/939102/

(which has been built and packaged for Arch)