Hey @Manixx, welcome to the Spotify Community!
As we look to improve the overall Spotify experience, we’re now automatically generating usernames, hence the random letters and numbers.
You don’t need to remember this to log in. You can access your account with your email address and password.
During signup, you can personalize your account by creating a profile name that’s displayed in the app. There’s no limitations to a profile name, so you can choose any name you like. It's not possible to log in with the profile name.
Take care 🙂