yarn is one of those things coming out of the JS world that is actually really well made. yarn, typescript, react; say what you want about js fatigue, these are rock-solid, well-tested projects that are really good at what they do.
A major reason for the high toolchurn in that ecosystem is how many of those tools are not designed from the ground up, don't quite solve the things they ought to, or solve them in really weird ways (due to the low barrier of entry partly). But that doesn't mean all of it deserves that label.
Can't say anything about react, but yes: yarn and typescript are good.
This is coming from a long time Java programmer who still likes Java and Maven but now might have a new favourite language.
This is made even more impressive by the fact that it is built on the mess that is js. (Again: I'm impressed that it was made in three weeks I just wish a better language had been standardized.)
A major reason for the high toolchurn in that ecosystem is how many of those tools are not designed from the ground up, don't quite solve the things they ought to, or solve them in really weird ways (due to the low barrier of entry partly). But that doesn't mean all of it deserves that label.