The big problem with growth mindset isn't the mindset itself, it's the theoretical framework and the broader milieu surrounding it. It would be one thing if the concept were simply put forward as a way of framing and thinking about certain differences in how people learn in certain contexts. But there's apparently now a faction of education experts who have decided that growth mindset is Right and fixed mindset is Wrong, and so we're failing children if we don't "educate" them into having a growth mindset. Even if that means totally ignoring their lived experience and making them fill in a bunch of worksheets that are basically just "Goofus and Gallant" for beliefs instead of actions.
Not only did it fail replication studies (as most psychology experiments do), but on a model analysis level it vastly oversimplifies things. The mind is a lot more complicated than growth vs. fixed mindset.