Fish version 3.1.0
Ubuntu 20.04
xterm-256color

This issue can be reproduced regardless of third party customizations are added or not.

Whenever an abbreviation ending with a single quote is added via fish_config UI, the single quote at the end gets stripped. Even if the command is wrapped with one more layer of single quotes.

So setting the word _first to awk '{print $1'} actually executes the following command:

abbr --add '_first' 'awk \'{print $1}'

Also setting the work _first with another layer of single quotes: 'awk '{print $1'}', results in the execution of the same command:

abbr --add '_first' 'awk \'{print $1}'