[rudasn]

Changing jobs because of the tech stack doesn't sound like the smart thing to do (you know, unless the teck stack is the root of other problems).

As others mentioned, if you are learning new things and you like it so, you can learn react (or whatever) on the side.

FWIW I would prefer a front end dev who has worked with vanilla js extensively and has real experience with the basis over one who has only worked with react or some other framework (if that's the only metric being used to assess their abilities).