This doesn't change anything, Google said 7 years of OS updates, not 7 Android versions. The device should be getting support until 2031 regardless of which android version it shipped with
It shouldn't change anything, but guess what, capitalism. They are referring to years, as in annual is updates, cause yk, android gets updated every year or so. But it's now become more of a 7 versions of is updates, as if t the update cycle is coming earlier in one year, they may have to develop another extra version for the device, which costs money. Kinda like a15 is supposed to show up rn on 13 august
What matters is when that date is set for (traditionally based on the day it goes on sale) and when the new OS comes out (7 years from now). This is also only the guaranteed support date. They can (and have) delivered updates after the guaranteed date.