My moment was using the experimental repos to get an early view into wayland, after seeing it wasn’t quite ready for my system I just switched back. Mistakes made, and slowly over the next few weeks as I updated, the experimental packages never got superseded and updated, until my system crashed and would not pass boot.

Luckily since it is not windows I just used a live usb stick to mount the disk and manually reinstall all the broken system packages. Scary but made me feel pretty confident I could recover the system myself in the future. Also learned a pretty important lesson. Don’t do that, and look at the upgrade log if you do lol, cause the whole time, as I upgraded there was red text showing me all the system packages that were not getting updated.