In the ideal world, there is no impact. However, there may be temporary supply-side pressure as some traders might sell out a portion of their shares. There is no sound logic as to why anyone will sell shares in a non-eventful corporate action such as a split. So yeah, nothing worth discussing.
A split is done mainly to make shares more affordable and reduce bid/ask spreads. Also, companies stock splits when the price has run up by a lot and comes across as expensive. They split the stock to make it appear less expensive from a share price perspective.
