It's not like the time spent learning it is wasted. The concepts are very transferable. I started a job last year, which involved working on a React Native app. I had zero experience with either React Native or React, but I could be productive pretty much right away, as I had lots of JavaScript and TypeScript experience so no problem with the language, and some experience with Angular, so could handle the concepts. My native iOS and Android experience meant I could write plugins too. Recently I had the slightly odd experience of helping to lead a class on React within a couple of days of using it for the first time. Aside from some fumbling with the styling, I could apply my React Native experience with no mode switching required.

Learning a new framework is rarely time wasted. Even my totally obsolete experience with Adobe ActionScript was really useful a decade later, as it's basically the same as TypeScript, while Flex shares a lot of concepts with React.