I've also played a lot less of Civ6 after NFP, but I place that on fatigue after like seven plus years of the game.I guess to me my own personal barometer has been when I realized that most of the fun/best CIV VI games I ever had were the ones that took place BEFORE the NFP Pass. I can't quite put my finger on why this is the case, but it just is.
I think the Game Modes were (mostly) a good idea, it's just the implementation was poor or they were ruined by bugs (esp. the Monopoly mode). I almost wonder sometimes if the Monopoly mode was a test run for some kind of "economic victory" condition for CIV VII (though that's probably just hopeful projection on my part).