It's completely inconsistent with traditional Windows design language and there's no "Cancel" button or an X in the corner to click on so you can't cancel out of it with your mouse and have to reach for Esc on your keyboard
It also tries to funnel you into a shitty Microsoft service
The biggest hurdles I run into are relating to software management. People expect to google up a .exe and run it.
What ever happened to those "download in ubuntu software centre" orange buttons I was seeing around? That was a damn good idea to bridge the gap while bringing users into the fold by making sure apt is aware of the program being installed, and that it's installed via official channels.
Does Mint still ship gdebi or whatever it was called?
Oh and don't get me started on snap. I always tell people to disable snaps from the software centre if they're installing a *buntu.
People that are installing .exe files from internet searches are beyond the beginner stage and have started getting the Windows brainworms. It's best to get people who never install anything except from the Windows store to move to Linux. The discover store in KDE is essentially the same thing.
I always say that your grandma is the best linux candidate in your life. Linux with XFCE works a hell of a lot more like what she's used to than Windows 10+, won't get viruses, and will do absolutely everything she would want it to, and will be faster than windows on her old laptop.
Set up BTRFS snapshots weekly and if something gets messed up just have her roll back to the latest one.