Small disclaimer: I’m not claiming all these issues can be said to be 100% Ubuntu’s fault, but if recommending a distro to someone who wants to try Linux for the first time they probably won’t care about anything other than the compound experience. I used Xubuntu for many years and remembered it as very stable and the vast majority of things being easy and working out of the box, which is why I was so surprised that I had to spend hours troubleshooting various things that I never had problems with previously.

Some issues and annoyances I remember off the top of my head:

Unable to wake computer after monitor turning off due to inactivity. Happened to all 3 computers which have very different hardware, which seemed a little strange to me. Did some troubleshooting on my wife’s desktop PC and IIRC it appeared to be the program which would ask for your password crashed, causing the computer to turn off the monitor signal again. Uninstalled the xfce4-screensaver package and disabled password on resume on her PC which fixed it there, but her netbook needs to have password and I think it still sometimes has this issue (she doesn’t use it very often). On the htpc I both uninstalled xfce4-screensaver and disabled all monitor power saving, but recently it has started turning off the monitor signal after inactivity anyway. At least it always wakes up from this state.

However, the htpc sometimes fails to wake up the monitor/tv after hibernate. The computer wakes up but the monitor doesn’t, and the only solution I know is the following procedure: Wake the computer up, press ctrl-alt-f1 to switch to a different vtty, press the keyboard shortcut to hibernate the computer, wake it up again, press ctrl-alt-f6 to switch back to the graphical desktop. For some reason that works…

Every time the htpc wakes up from hibernate there’s a notification saying something about the computer being reconnected to the network. There’s a button on the popup for “don’t notify me about this again” but it makes no difference, the popups keep coming. Can ofc. be disabled entirely from some other settings, but it’s not working as expected.

Watching movies in Kodi doesn’t work. It starts playing it without sound, then it begins to stutter after about 10 seconds and it gets worse until Kodi freezes entirely. Haven’t had time to properly debug it, but it worked just fine on Arch (which I wouldn’t recommend to a beginner for other reasons :)) which the previous htpc had. Instead we use VLC for the time being.

We watch various series on youtube and dropout.tv so we have a browser tab permanently open for each, often with longer episodes paused in the middle. About once per month there’s a popup telling us that we must close the web browser so that snap can update it. The popups don’t time out, and need to be clicked to go away. If you click to ignore it too many times it will forcibly close eventually. Occasionally this causes the web sites to forget what we were watching, and it can take a bit of time to find out where you were in a 3 hour D&D actual play. Probably snaps working as intended but both of us find it annoying.

Over all our Brother laser jet + scanner is great with Linux, but I had to spend a few hours to get all features working on my wife’s PC while it was pretty much plug-n-play on my current install of Fedora KDE.

Wife’s PC had issues with monitors losing their relative position and orientation. It might’ve been triggered when one of the cables glitched a bit, and it doesn’t happen now that they’re screwed in properly, but I think the OS ought to remember the configuration better. It also moved the monitors so they weren’t adjacent, which made the mouse pointer behave very weirdly when moved between then until she rearranged them in the settings.

There were some other things that I’m not able to recall right now too, nothing too serious for someone with Linux experience. My wife used Ubuntu at university so she’s not computer illiterate, but I don’t think she would’ve had the time and energy to spend hours troubleshooting issues, searching online and digging around in config files, so she probably would’ve switched back to Windows since it mostly worked for her.