I have been using old. on desktop this entire time. And, even on mobile ever since the API-pocolyspe.

What is the default feed for normal users on desktop and in the mobile app? I guess I have no idea if I'm being honest.

No idea, I use old on desktop with RES and not-logged-in web on mobile, which is trash.

"home" I guess - "popular" is the top menu item right next to it in old reddit interface ("HOME POPULAR ALL MOD USERS").