The requirements are chaotic, there is no fix roadmap for the project. As a frontend engineer you need to adapt to their way of working which is as i said, chaotic.
The PM says we need this, then the entire team need to come up with the business logic and implementation. And all in a fast paced environement. Moreover, the async way of work can be nice if you know what to do. But as a 2-3 months employee, on this huge product, you will not be able to.
Biggest con, if you don't adapt quicly to their way of working, and give 110%, then you're are replaced.