Same on VW’s too, so it might be a VAG thing across all VAG brands.
Edit; just done a bit of research. The delay is there because there isn’t a non-return valve in the flexible tubing from the washer fluid reservoir to the washer jets, meaning any residual washer fluid in the tubing after washing the screen drains back into the washer fluid reservoir.
Can sometimes be annoying, but stops washer fluid freezing in the flexible tubing during the colder winter months, which is probably why it was designed that way.