I completely agree. One of the things I find more stressful is the lack of time to dive deep into new stacks while meeting deadlines and delivering on time.

Maybe a side project would be helpful. I personally have considered implementing an MVP for a personal project using a stack I already know, and then gradually reimplement different parts with newer technologies.

Having a solid set of integration / E2E tests would probably easy the transition and help overcoming the If it ain't broke, don't fix it feelings that might later show up.