Serialization doesn't work. Passport js. What to do?

Question

Express.js

I am writing an application on the MERN stack.
Made authorization through Passport JS. Upon successful authorization, the username must be serialized and retained for further access to the session, but this does not happen. Moreover, in applications similar to postman, everything works correctly (I checked it on several), but the browser does not.
I checked all requests on the client side. Everything is correct. Authorization fires, but the username is not serialized.
What do you suggest?
Code: https://pastebin.com/zcA6VNe5 (server.js)