Literally just makes Ctrl+R refresh the server selection screen.
Fun fact I discovered while making this: f5 also refreshes the page in vanilla.
This might work on 1.16.5 and below, but in my testing, I was getting a bunch of errors about the java version and mixins, but if anyone is actually, unironically using 1.16.5 or lower on fabric (aside from speedrunners), that's your problem.