AFAIK the macOS activity manager doesn’t show task usage as you’d expect. It displays resource usage based on total current usage rather than maximum capacity.
Citation needed. That doesn't match my experience at all. When Activity Monitor shows high CPU in the process list, it corresponds to high CPU in the CPU monitor.
I have the same machine and none of those issues.
Probably yours is broken somehow. Would recommend bringing it in for service while it's in warranty.
The fact that I can point at both colleagues and strangers on the internet with the same issues makes me think it's actually just crap software that doesn't work.
I think if that were the case there would be a lot more people with the issues you’re talking about.
My whole shop uses Macs and nobody has this issue. I’m on one of three different variant MBPs (including one like yours) all day every day - literally around 18 hours a day - and I’ve never seen it.
That’s why I would really suggest opening a ticket on it, especially with a new laptop. I suspect there’s a hardware issue.
I have a 2019 mbp16. It does not "work well". For me, the graphics driver crashes me out of my login session pretty much daily, the network stack occasionally shits itself (reboot) and various internal processes (the... window server?) like to use >50% CPU for no reason at all.
Looking around, I'm not the only one who has issues.