Got this report from one of the server owners on my modpack:

You can use an auto clicker before the fishing minigame to make the game think you have way more fish on the line
the laggier a person is the more you catch (averages around ~10 per catch)

My guess is because the client is sending multiple of the hooked events to the server and instead of overriding the current action it's causing it to fire multiple times. I haven't had the time to sit down and look at the code though so not sure if that's what's going on.

Wow, thanks for reporting that! I have a 3.0 update ready to release, so I'll make sure to include a fix.

3.0 is now released with the autoclicker fix!