@Nasser I mean E^(x*Log[a]) gives a^x without Simplify[]. So even if Simplify[] or some other code gives E^(x*Log[a]), it will automatically become a^x. I don't see how to stop that from happening.
@MichaelE2 oh, I see what you mean. I did not notice this as I did Simplify[] on it. This looks like one of those auto-simplifications done by the interface before it gets to the kernel? I also do not know how to stop this. May be there is one of those secret system options that does that.