Anyways recently the typescript backend scene is developing a lot better than even a few years ago. stuff like NextJS becoming more popular and more stable better backend typescript frameworks coming out.
My comment was mostly aimed at using backend languages for frontend as opposed to necessarily targeting Typescript
FWIW I was a primarily a Java server developer for the first ~15 years of my career, then switched to Node and really loved it. It was at that point that I fell into the benefits of my "Typescript everywhere" mantra because it solved so many problems I had seen with the common setup of Java on the backend and Javascript with the rise of SPAs on the front end.
I am curious - could you explain how you are benefiting from using Typescript on both back and front end?
When I've posted this before, the main objections I've got have usually been from the perspective on individual developers, or stuff like "you can't actually share a ton of code between front-end and back-end". That's not my primary point (though there are some places where it is nice to share code, e.g. input validation that you may want to run on the client for user experience/performance reasons but then that you also need to run on the backend for security reasons). The biggest benefit I've seen is in team dynamics which results in bugs getting fixed faster and new features getting added faster because it's easier for team members to "cross" backend/frontend boundaries.
We switched over, have fastapi generate an openapi.json, then use Kubb to have it auto-generate typescript types (it can also do zod models), done.
Note I'm not saying do this everywhere if there is a place where there are clear benefits to using another language. For example, while IMO the difference between Python and Node on the server for standard CRUD type apps is really one of preference, that's not the case for doing something with ML or LLMs, where the ecosystem around Python is much bigger, robust, and more generally familiar to the AI crowd.