It's simple parallex error D: Especially if you are the type of players who look high up and centred. The fruit that's falling on the far left/right is furthur away from your eyes than if it falls in the centre of the screen, therefore:
1. You are likely to encounter slight delay in reaction.
2. The speed of your catcher seems to be different when travelling to the sides as compared to travelling to the centre.
It's like when a car travelling at a constant speed far away it looks like it's approaching you very slowly, but when it gets closer and closer it seems to be going faster and faster. That's what you see your platter do when it goes sideways, it seems to travel at different speed, it'll affect your judgement.
How to solve the problem:
1. Have better frame rate/refresh rate, so your graphics is smooth to read.
2. Wear spectacles if you don't have good sight.
3. Look down low instead of high up.
4. Read each fruit individually instead of just looking at an area.
5. Play more and get used to it.
6. Follow the rhythm as much as possible so you rely less on pure reading.
Of course there are downsides to above proposed solutions:
1. For low end PCs this will cause lag and overheating.
2. Tiring for the eyes if you are not used to viewing through lenses.
3. You'll have trouble reading high ARs and Hidden.
4. You tend to miss offscreen/offsight jumps more.
5. Huge investment of time and effort needed.
6. There are times where difficult parts have no distinct rhythm to it, happens often in standard converts.
Try to find what suits you best. Usually you will get use to such thing at about 100 hours in 10,000 play counts. If you still can't keep up after a lot of drilling then maybe you should try static modes like Taiko and Mania where control of movement of hitbox is not involved.
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