I came across both usages but can't really tell when one is used over the other or discern any subtle difference. Is it a question of American or British English?
"React on" seems certainly much lesser used than "react to" (see Youtube & Co.). Could someone maybe give some more examples, in case it's just about common phrases like in a figure of speech? Dictionaries only seem to know the latter [1] [2] [3]. Somewhat related, this about whether it is also possible to use at. Answers here indicate that one can only use "to" in combination with "react". Does that mean "on" is always wrong?
Learn English – What’s the difference between “react on” and “react to”
differenceprepositionsword-choiceword-usage
Best Answer
We react to a stimulus or situation.
The preposition on would not head a phrase which refers to that which is being reacted to; it might be adverbial, for example:
Or on could refer to something which is affected:
From a grammatical perspective, the plastics are not the stimulus. There is a reaction when the chemicals are applied to plastics.
We could say:
But people often say that the one thing reacts on the other.