I'm really curious about this deterioration? I use a M1 Macbook Pro with 16GB RAM as my primary machine and it still runs fine. I do iOS development so it's not exactly fast but I wouldn't call it slow by any word.
My Poor M1 Mini though is struggling though but that's b/c I'm running it as home server and 8 GB RAM is not enough anymore.
Different people are sensitive to different things. I still find my 6th gen ULV i5 and 8GB of RAM tolerable.
Curious about the choice of the Mac as a home server. I feel like an off-lease x86 usff pc, at roughly half the cost, would be more useful as a server. Pre-RAM-crisis you could get one with 32GB of RAM for like $240. My main home server is one of those HP ProDesk, running Debian.