This might be a useful question but what would you consider to be an appropriate lifespan for your machine before you replace it?
We don't yet know when Apple will start pulling macOS support from Apple Silicon. We know Intel support will be dropped with macOS 27, so the earliest the M1 Pro/Max MBPs from 2021 could lose support is macOS 28 in 2027. (And even then I would be surprised by that).
Apple typically provides security updates for 2-3 years for a given macOS release, so it could be 2029-2030 by the time you lose security update support. You could extend that another 1-3 years by switching to a third party browser like Firefox, Brave, Vivaldi, or another privacy and security-focused option.
That could easily extend you to 2031 which would make the laptop 10 years old. That seems like a good extended lifespan for a device, and again that would be contingent on it losing OS support in 2027 as opposed to 2028 or even 2029.