Resolved: Change Java 11 back to Java 8 with sudo update-alternatives --config java
and restart the launcher. Older versions will now work.
There should probably be a Launcher prompt to make this clear.
Additionally, the newest version of the Linux Minecraft launcher will crash old versions (pre-1.14.4) versions of the game when trying to launch them. Running in terminal will say "SaveToBuffer failed".
Sorry,but my C key physically is broken and I cannot force a crash.I insert C keys using a on screen keyboard and therefore cannot force a crash while in game.
Change Java 11 back to Java 8 with
sudo update-alternatives --config java
and restart the launcher. Older versions will now work.
There should probably be a Launcher prompt to make this clear.