The extra Bonus Attack on the Thief that helps make dual wielding viable needs to be removed. That is not the correct answer.
Mostly because other classes and subclasses need to be able to dual wield as well.
But also because extra BA's open up new problems. Drinking an unreasonable amount of potions to tank a hard enemy. Using powerful stuff like Wyvern poison or smites spiral out of control when you get extra attacks.
I agree they should already change how dual wielding works in BG3 (as per the One D&D playtest material) and get rid of the Bonus Action requirement.
