While I agree it is unlikely, it is not impossible.
He already replaced the CMOS battery not long ago. But again, it is possible the new one has failed prematurely. That could indicate a bad battery from the factory
OR faulty component in the circuit draining the CMOS battery or putting a "low" on the CMOS circuit - in effect, resetting the BIOS, at least in part.
And again, despite what some here are claiming, this is NOT normal. Just because you remove power completely, your system should NOT forget these settings. The CMOS battery should hold them, assuming the battery is good - that's its job. I will note, however, this seems to be a common problem. But make no mistake - once set, the settings should hold and do hold for the vast majority of users.
My friend Bing Google is finding where several folks are reporting problems and bugs with memory settings getting lost after a cold boot.
BUG: Memory Fast Timing not applied on cold boot, Option in fact broken until manual reboot : Amd (reddit.com)
[SOLVED] x570 / 3900x Cold boot BIOS reset. - Troubleshooting - Linus Tech Tips
FTR, I never remove power completely from any of my computers, unless doing maintenance, or another major storm rolls through my area here in
Tornado Alley. The only setting I occasionally lose after extended outages is the IP address assignment from my router.
Losing settings just because power is removed is unacceptable and definitely not normal.