I have a similar issue. On my first PC, I have enabled syncing my data including passwords. I created my Opera account by signing in with Google. Therefore, I don't have a password for my Opera account. But on the second PC, Opera wants me to provide such a password on https://auth.opera.com/account/v3/desktop/login/confirm-password in order to confirm my identity for password syncing. The "Sign in with Google" option is missing on this page (I was able to sign in with Google on the page before)... What should I do?

The encryption option is set to "Encrypt only synced passwords with your Opera account credentials".

@leocg Thanks, it finally worked
Is it intended that the wallpaper and installed extensions aren't synced?

@leocg This page redirects me to https://auth.opera.com/account/edit-profile
At "Password Set a unique password to protect your Opera account." I can only click on "Change". Then, I should enter the Opera account password I don't have anymore, no button for resetting it.

@leocg Maybe, I don't remember... how can I retrieve or reset the password?

@leocg Yes, password is wrong. At first, I can login with Google, but the linked page wanting an Opera account password is loaded next. I'm even greeted with my Opera account name here.

@leocg Doesn't work, the page I linked accepts only Opera account passwords.

@leocg I don't understand My current Opera account is my first and only one. I created the account with the Google sign-in feature and use it for login in, too. I have no clue how to sign in without Google as I don't have a password.

I have a similar issue. On my first PC, I have enabled syncing my data including passwords. I created my Opera account by signing in with Google. Therefore, I don't have a password for my Opera account. But on the second PC, Opera wants me to provide such a password on https://auth.opera.com/account/v3/desktop/login/confirm-password in order to confirm my identity for password syncing. The "Sign in with Google" option is missing on this page (I was able to sign in with Google on the page before)... What should I do?

The encryption option is set to "Encrypt only synced passwords with your Opera account credentials".