I found an annoying but, its not terrible but everytime I install something or restart my computer the volume automatically goes back to 40%. I do not know if this is something within KDE or a bug. Either way just wanted to make you aware.
I was having the same problem and can confirm that this workaround fixed it for me. Changing it only in the wireplumber.service file was enough to fix it.
EDIT: I may have spoken a little too soon. It usually remembers my volume setting after rebooting now, but sometimes it gets set back to 45% again.