You can learn any framework and get good at even while on a project, in just a couple of months. The problem is that there are too many things to learn in terms of tooling and frameworks all the time making you have less time/bandwidth for the actual domain problems which are why you have the said job. Getting good is one thing and becoming an expert is another. Because these frameworks lifetimes you don’t want to become an expert over and over again on things that become obsolete because it takes a lot of energy and the payoff is short term.