If you make an application as SPA, then it's no difference, what you use on client and on server.
SPA means you have client as independent application. It's almost self-sufficient application like usual client for client server application. Server application is just API + static serving.
Client doesn't much depends on server app. language and vice versa.
Another thing if you want to make not SPA, or SPA with Server-Side rendering or NuxtJS app. Then you usually need NodeJS interlayer.
What about me, I tried to make a small SPA Todos with Flask and Vuejs, and I use this stack for examples in my Web-development course that I teach in university, because it's easy to understand without much scary code etc.