Any way to disable artificial difficulty?

I'm still pretty new to the series, about 500 hours over the last three iterations. But one thing that constantly annoys me is the artificial difficulty of certain matches (rivalries, cup, Europe, etc). Just to check I created a team of all 20s across the board, yet I would lose to teams like Everton in the FA cup finals (yeah.....), or rivalry games against terrible teams. But then regular season matches I could do 15-0 regularly, which tells me it's completely fake difficulty.

I also put everyone's "important matches" stat to 20 but it makes zero difference. Is there any practical way to combat this? Thanks for any advice!