I switched to Linux about 1.5 years ago now when replacing my old Macbook Pro with a Tuxedo Infinity Book. I am super happy with the transition, and for the most part my digital life has severely improved as a result of it. There's one thing in particular though that I haven't fully grasped or understood despite all the talk about it, and that really has mostly caused confusion on my part, and that is Xorg/X11 (I don't know the difference...) vs. Wayland.
I started out with Tuxedo OS 1 and 2 running KDE Plasma 5.x.x, and thus have been on X11 for the most part since switching to Linux. I never dared switching to Wayland myself. However, they somewhat recently started offering optional upgrades to Tuxedo OS 3 running KDE Plasma 6 where Wayland is the default, and I took the plunge. The only real difference I noticed was small annoyances that I had to fix. Glitching windows running on XWayland and having to configure some .desktop-files to force apps to launch natively in Wayland. Apps not showing the correct desktop icons but the generic Wayland logo instead, making Alt+Tabbing a bit more difficult because it is harder to tell applications apart. Annoying smooth scrolling (I don't want scrolling to have as much friction as polished ice) activated in all kinds of applications that I seem to have to turn off individually. Nothing breaking (though I haven't dared booting with my Nvidia dGPU yet in fear of breaking something irreversibly...), but I haven't noticed any improvements either, and I find it a bit frustrating not knowing where to make the necessary changes and always having to search for it seemingly on a case by case basis.
Now for instance I was updating FreeTube to a new version, and the flags I previously added to the ́.desktop'-file suddenly doesn't work anymore (--enable-features=UseOzonePlatform,WaylandWindowDecorations --ozone-platform-hint=auto). The application won't launch unless I remove them, but then it launches under XWayland instead. Not that I have any issues so far running it like that, but I guess I would prefer to run everything natively in Wayland if I can.
I can explain the difference between X11 and Xorg with an analogy to the web and web browsers: X11 is like HTTP, Xorg is like the Chrome browser. X11 is the protocol, Xorg is software that implements that protocol.
X11 is old, it was designed back in the 1980s and includes messages for drawing lines and circles and fonts on the screen. Also, back then there were a lot of "thin clients", computers that were basically nothing but a browser, since graphics were computationally expensive and could not be done on the client computer, graphics rendering was done server side. There are lots of messages in the protocol for handling screen updates over a computer network.
Nowadays, all personal computers are powerful enough to render their own graphics, and no one needs the display server to draw individual lines or circles on screen. Vector graphics and fonts are done at the application level, not over the network. So these these messages specified in the X11 protocol are hardly ever used. Really, most of X11 (let's say 90% of it) is not used at all, only the parts where the keyboard and mouse are defined, and how you can allocate memory to buffer a graphic and copy that buffer to the display. But you still need to maintain the Xorg software to handle everything that X11 specifies, and this is just a waste of code, and a waste of time for the code maintainers.
So basically, they decided about 10-15 years ago that since no one uses most of X11, let's just define a new protocol (called Wayland) that only has the parts of X11 that everyone still uses, and get rid of the 90% of it that no one ever uses. Also, the protocol design takes into account the fact that most modern computers do all of their own rendering rather than calling out to a server to render for them. Also the Wayland protocol design takes into account that a lot of computers have graphics cards for accelerated graphics rendering.
Since the Wayland protocol is much simpler, it is easier for anyone to write their own software which implements the protocol, these software are called "compositors." Finally, 10 years after some of the first implementations of Wayland, the protocol and compositors are becoming mature enough that they can be used in ordinary consumer PCs.
Don't forget Wayland and security into the mix as well. That seems to have caused some of the biggest issues with apps. Don't get me wrong though, security was desperately needed. X11 had no concept of security.
Do you mean that Wayland has had its own security issues, or that enhanced security has caused additional issues for apps to run correctly?
My understanding is that due to X11's design, all running GUI apps can "see" all the other apps. If you're running a malicious program in X11, it can easily snoop what else you are doing, log your keystrokes, etc.
Wayland solves this through better design.
The second one. Some apps were taking advantage of the fact that X allowed any program access to EVERYTHING on your screen, shortcuts, etc. Wayland ensures more control, which is excellent news, but definitely the change requires programs to adapt, and some have not (AnyDesk, for example).
The addition of security has caused issues.
E.g. apps not being able to see other apps by default has caused issues for some screen recorders or screen-sharing software. Or screen readers from seeing inside apps.
Or apps not being able to see keystrokes when the app isn't active, impacting global shortcuts (say, for example, you're a streamer who uses a hotkey to change cameras in OBS)
A lot of Linux stuff was written with the expectation of there being zero security safeguards. With Wayland, that has changed and it's causing issues.