Diminishing Returns is a system in Tales of Arise that forces players to vary up their combos. Each time you repeat the same combo order in your attacks, parts of the combo become weaker. The effect triggers if the player uses one combat arte more than once during a four action sequence. So if you press Y twice in four button presses, the second Y attack will be weaker.
The biggest impact this has is to reduce penetration, lowering damage done to enemies. This effect can magnify against resistant enemies that further reduce DPS.
And since the effect can trigger on any character in any four attack strings, it gets kind of hard to have a set pattern to your attacks. It’s very natural for players to fall into a rhythm with their attacks.
So how do you avoid this? The general consensus is that you need to keep changing the order of your attacks to prevent the effect from taking hold. There are a few ways you can accomplish this. One way is to do aerial attacks.
Look at your combo lists and note any moves that have an upward arrow next to them. Both Severing Wind and Rising Wind have this arrow. That mark means the character will launch into the air as part of the combo string. You can alter the flow of your attacks and Diminishing Returns in combos from triggering by using this trick.
The other way you can avoid Diminishing Returns in combos is to just use a different button. If you pressed A at one point, get into the habit of swapping to Y or another button. So just go out there and keep things switched up, and you’ll be fine.