Aside from potential security issues newer versions of windows always provide new APIs and changes to old ones. Keeping support requires keeping track of that and testing, which costs resources.
There is actually dilemma about potential security issues; since the development has been stopped, no new features are introduced and hence no new bugs.
Windows 7 is quite battle-tested.
Can the system be so stable that there aren't security issues anymore?
On the other hand, one is too much if it is not fixed.
> windows always provide new APIs and changes to old ones
I don't think that is visible or significant. Windows changes APIs but always provides backwards compatibility. It is the major reason why it is dominating in many industry areas. You can run Windows 2000 apps in Windows 11.
