The Feature Class to Feature Class (deprecated) allowed dynamic Output Name using string variables, which was very useful for adding timestamps and differentiating model runs.
The Export Features GP tool (replacing Feature Class to Feature Class) no longer allows model variables to be used for Output Name. This eliminates the ability to easily add timestamps to exported feature layer names.
As there does not seem to be a way to match previous functionality, I have also posted this as an idea.
Match previous functionality of Export Features to... - Esri Community