On the registration page (/register), the validation of the password confirmation happens in reverse. The correct procedure is to validate only after entering the password confirmation.
In Nop.Web / Validators / Customer / RegisterValidator.cs simply reverse this way:
RuleFor(x => x.ConfirmPassword).Equal(x => x.Password).WithMessage(localizationService.GetResource("Account.Fields.Password.EnteredPasswordsDoNotMatch"));