Golf putting -Difficult fast greens?

Recently played on a tough course with slick fast greens.

Of course in this situation,on downhill slope much less force is needed to hole the ball.

My question is regarding a couple slightly uphill putts. They did not go hand in hand with the slick greens. They were hit with slightly less force than I usually hit for uphills and both landed 5-10 feet short.

1. Are the speed of the greens not a factor with uphills? I assumed just like a reg. putt on a fast green,you had to be careful and hit with a shorter pendulum.
or
2. Is this a normal part of golf course design-to make the greens more difficult/tougher to read? (On TV you see even the pros with the confused,w.t.f? look when a putt goes where it seems shouldn’t)
Putts were from around 20-25 feet

The speed of your putts has a lot to do with the grain of the green as well as more obvious factors like uphill/downhill.

Typically putts that go against the natural grain of the grass will require more force to go the same distance as a putt that goes with the grain.

Here’s a tip from a tutorial on reading greens: "Look at the green from all angles in the early morning or afternoon sun. Depending on how high the sun is you may have to squat down as low as possible to see the grain.

The noticeable sheen you see means that you are looking directly down or with the grain. Putts hit with the grain roll more smoothly than against the grain but, more importantly, they roll further."