https://www.gamespot.com/articles/free-sea-of-thieves-expansion-delayed/1100-6461818/

The next free Sea of Thieves expansion, Forsaken Shores, is not going to launch on time. In a blog post, developer Rare said the expansion will now launch on September 27, which is about one week later than its previously announced September 19 date.

Rare did not reveal a specific reason for the delay, but the UK studio said in its blog post that the extra time will help the team deliver a "stable, polished, and bug-free experience."