Thin scroll bars, cookie consent messages, bloated web content, micro HDMI connectors, automated feature updates. These are the things that currently annoying Christopher Barnatt of Explaining Computers.
Partly, it's linked to the fact that of course, Windows 10 is not an operating system. It's a number of operating systems that changes twice a year to be a different operating system. And Microsoft takes things out and adds things in gives us new features, apparently, which many of us didn't want in the first place. It's extraordinary. I can't think of any other area of product or services, where you buy something, and you use it. And its features change, without any consultation with the user, often for the worse.
In case you missed it, here's Barnatt's 2017 video of 5 other computing annoyances.