I tried to login back to my account via Email (verified code which came to my inbox), via Google, via Github. No success at all. No matter what I do, it says “Oops! Something went wrong. Please try again in a moment.”
Now I can login, thanks for quick response!
Here is how solved: I originally singed up for FCC learning (not forum, which is separate account) with my GitHub account, which is connected to my gmail. Turns out, later I’ve changed my FCC account email to hotmail. I tried again via email using hotmail, now it works.