Candy crush in the sidebar, ads all over the home page/new tab page of the built in browsers. Heavy annoying pushes for Microsoft products like starting Microsoft teams every time you boot when I never installed it or even have an account.

I have yet to see ads also, but I do turn off all the unnecessary stuff at installation time. There is this option on Lock Screen settings called Get fun facts, tips, tricks and more on your lock screen and Show more tiles on the Start settings that can bring stuff out and probably some other more spread around, of course they won't make it nicely like Opt out of all ads across Windows just because.

IIRC, start tiles, explorer bar, stub shortcuts.

Give a non-technical user a copy of Windows 10 and Chrome, wait a few days for the third party ad networks to catch up, and then watch as advertisement after advertisement pop up in the lower right hand corner.

I'd also like to mention the Microsoft News program as being an annoying delivery mechanism for such content (it seems to have some relationship with the browser based on how the user uses the Internet).

Also the logon screen that is now delightful except someone has sold on the idea that they should add clickbait ads for msn and bing - even on pro and enterprise Windows..!

I imagine management in Microsoft is like a fight in the wheelhouse:

Someone trying to make the best OS there is.

Others trying to do ads everywhere like Google.

Some trying to be a reaponsible reliable company, others somehow managing to to crazy price hikes.

Some trying to be friends with open source, others pushing Edge really hard (but, in fairness, still not as ugly as Google was pushing Chrome at its worst.)

Etc etc

If you use the windows search in the bottom left corner, you'll see all sorts of advertisements when you search for stuff on your computer.

Same. I suppose if you view lock screen as an "ad"... I built my own 10 home box which has had no problems for years now.

If you turn them off you dont see them. It's a dark pattern but not completely black.

In the start menu.