That's not Google's/Android's fault, it's your device's manufacturer's fault. Nothing stopping Lenovo from releasing updates for 5-10 years if they want, they just want you to believe it's obsolete and hope you'll buy a new one from them. I mean, it's a Lenovo, what did you expect?
The ultimate proof it's manufacturer laziness is that custom ROMs like LineageOS have updates out before the manufacturer does, if ever. I have a Galaxy S7 working just fine on Android 13, upgrade all the way from Android 7. Still runs smoother than the OS it came with too.
I was able to install Lineage on my Galaxy Tab S5e and it went from I think 11 (last supported version from Samsung) to 13. It's cool how these custom operating systems can bring fresh life to a so called old device.
This is exactly why I do not buy android. I’ve been so close to switching from iOS so many times. But I keep my devices for a long time before upgrading. I always stop pushing through when I think about support for updates from the manufacturer.
There's a huge difference between brands when it comes to android. Samsung now provides four os upgrades and then security patches for a bit after that so that's 4+ years of support.
Fairphone has an even longer support time. I think it's 5 years? Maybe more, not quite sure.