I am speaking about the science of translation in general.
Not the different manuscripts being used to translate but the decision as to why a certain Greek word should be translated into a certain English word.
There are cases where a Greek word occurred only once in the NT and there are no known contemporary examples of that word in other documents from the first century.
We have discovered documents where some of these words were used and this helped confirm the best English word that should be used.
We have learned a lot since the KJV translation.
But most importantly when discussing why NIV, ESV, CSB, NASB might have slight differences in wording from the KJV one must consider the challenges of translating from one language to another and especially ancient languages into another. There will be slight differences of opinion even if they are working off the same manuscript and one must read the explanations of the translators to understand why.
This making a big deal about slight differences in English words from one translation work to another is not a conspiracy or a matter of evil motives.