Take Photoshop, for example, first released in 1987, last updated yesterday.
Use it and you can see the two ages like rings in a tree. At the core of Photoshop is a consistent, powerful, tightly-coded, thoughtfully-designed set of tools for creating and manipulating images. Once you learn the conventions, it feels like the computer is on your side, you're free, you're force-multiplied, your thoughts are manifest. It's really special and you can see there's a good reason this program achieved total dominance in its field.
And you can also see, right beside and on top of and surrounding that, a more recent accretion disc of features with a more modern sensibility. Dialogs that render in web-views and take seconds to open. "Sign in". Literal advertisements in the UI, styled to look like tooltips. You know the thing that pops up to tell you about the pen tool? There's an identically-styled one that pops up to tell you about Adobe Whatever, only $19.99/mo. And then of course there's Creative Cloud itself.
This is evident in Mac OS X, too, another piece of software that spans both eras. You've still got a lot of the stuff from the 2000s, with 2000s goals like being consistent and fast and nice to use. A lot of that is still there, perhaps because Apple's current crop of engineers can't really touch it without breaking it (not that it always stops them, but some of them know their limits). And right next to and amongst that, you've got ads in System Settings, you've got Apple News, you've got Apple Books that breaks every UI convention it can find.
There are many such cases. Windows, too. And MS Word.
One day, all these products will be gone, and people will only know MBA-ware. They won't know it can be any other way.