I just tried replaying this game, and I couldn't figure out why catching fish was so much harder than before. Turns out, after upgrading my monitor from 60 hz to 180 hz, due to me not factoring the delta into the rod speed calculations, the game difficulty depends on the frame rate. So 180 hz is essentially 3x harder than 60 hz.
If you're having trouble catching fish, cap your monitor refresh rate, lol.