My only guess would be that the flotilla relaunched faster than anyone thought it would so the writer just updated the article. Looks like they departed Sunday, turned back on Monday, and relaunched within the same day (maybe even just a few hours).

It already turned around due to bad weather

https://www.reuters.com/world/middle-east/aid-flotilla-heading-gaza-returns-barcelona-due-stormy-weather-2025-09-01/