Is fine, the S9 series are the only phones able to received 3 major updates (from oreo: Android 8, pie: Android 9, Android 10: one ui 2.0 then lastly 2.5), so am happy with it.
That's counted as 2 major upgrade. Android 8 was the default OS, and another "two" major upgrades for Android 9 and 10.
Starting from the Galaxy S10 series, they will all get 3 major upgrades. My phone, a Galaxy S10, came with Android 9. It received Android 10, and will get Android 11 and 12 in the future. So 10, 11, and 12; 3 in total.
That's a wrong interpretation. Only a change in major version number is counted as a major upgrade. This is how it works. One UI 2.0 to 2.1 and 2.5 is just a subversion update, as oppose to 2.0 to 3.0 (disregarding what comes in between, like 2.1 and 2.5).
My Galaxy S10 started out at One UI 1.0, then to 1.5, 2.0, 2.1, 2.5, and soon 3.0. All that, from 1.0 to 3.0, are only counted as 2 major upgrades. Since we're getting 3 major upgrades, it should be at 4.0 next year.
Same thing goes to iOS and Windows. Only the major version number is considered. Change in the subversion or the build numbers are not counted as a major upgrade.
