espresso pre-infusion explained 2

https://espressopuckpreparationguide.novacrestiq.com/posts/mastering-espresso-puck-preparation-the-foundation-of-great-shots

Pre-infusion is that short pause when water first hits the espresso puck, wetting the grounds before full pressure kicks in. It helps ensure even extraction by letting the coffee bloom, much like with pour-over brewing. Without it, water might channel through weak spots, leaving some coffee underextracted. A few seconds of gentle soaking can make your shot taste more balanced and sweet.