I'm having trouble with FactoryBot.
I'm getting an error in RSpec's system specs and I don't know the cause.

I had a problem trying to test if I was able to log in successfully with RSpec's System spec.
At firstbeforesoFactoryBot.createI created user data in db and tried to test the login procedure, but an error occurred.

RSpec.describe "User login", type :: system do
  before do
    @user = FactoryBot.create (: user)
Failure/Error: @user = FactoryBot.create (: user)
     ActiveRecord :: RecordInvalid:
       Validation failed: Email address already exists
What I tried

Only one user factory is created in the spec directory.

rails console --sandboxWhen I checked in, there was no duplicate email address, but when I quit the console and rolled back, I found that the user's id was abnormal.
First on the consoleFactoryBot.create (: user)When I created a user with, the id is 10, roll back and try againFactoryBot.create (: user)When I created a user with, the id was 11.
User.allWhen all users are displayed with, it becomes 1 ... 10 at first, but when it is rolled back and a user is created again, it becomes 1 ... 9, 11 and id = 10 disappears, and when it is done again, 1. It becomes .9, 12, and 10 and 11 disappear.
In other wordsrails console --sandboxIn the pastFactoryBot.create (: user)Only the id of the user created in was omitted.

somewhereFactoryBot.create (: user)I wonder if RSpec got a validation error because the data created in step 1 remains. I thought, but since I am a beginner, I have no idea what the cause is and where the problem is.

You can use a sequence in FactoryBot to generate a unique email address and I think this test will pass, but I'd like to fix it here as long as I know there's an obvious glitch.

Could anyone lend me some wisdom to solve this problem?

Supplementary information (FW/tool version, etc.)

The environment is as follows
Mac OS Catalina 10.15.7
Ruby 2.7.1
FactoryBot 6.1.0

The factory is as follows.

FactoryBot.define do
  factory: user do
    name {"factory_user"}
    email {"[email protected]"}
    password {"password"}
    password_confirmation {"password"}