The practical trade-off is that it is very, very difficult to secure a modern browser. Major vendors employ large teams of full-time security engineers and still ship vulnerable code with regularity. Companies such as Brave don't, but they get the benefit of getting many of the Chromium security features for free. Ladybird won't.

The thing that works in your favor is that Ladybird is very niche at this point, so unless some well-resourced adversary hates you specifically, it's unlikely that you'd be targeted.