When should you use BFF?

Question

JavaScript

In what all the same cases is it worth additionally making a BFF layer for your SPA application? Those. write a server on a node that will proxy requests to the real backend and do various other things.

I read a lot, but have not yet come to the conclusion whether I need this layer. While it is clear that the BFF layer helps to hide secrets on its side (so that tokens do not shine in HTTP requests), with this you can hide the real handles for the API, you can modify the backend response for transmission to the front. Maybe I missed something?