Touch a record in Rails Minitest gives different time on two columns

I have a simple test

test "should store activation time when activated" do
  profile = create(:raw_profile)
  get profile_activate_path(profile)
  assert_equal profile.updated_at, profile.activated_at
end

And a simple Profile method without any after_action or anything it's straightforward

def activate
  @profile.update_columns(active: true)
  @profile.touch(:activated_at)
  redirect_to @profile, notice: "Profile activated."
end

But the test fails with always a 2s or 3s difference

--- expected
+++ actual
@@ -1 +1 @@
-Sun, 23 Aug 2020 19:33:51 CEST +02:00
+Sun, 23 Aug 2020 19:33:49 CEST +02:00
test/controllers/profiles_controller_test.rb:73:in `block in <class:ProfilesControllerTest>'

An actual record in the console (or in the app itself) behaves correctly

>> p.touch(:activated_at)
   (18.1ms)  BEGIN
  Profile Update (2.2ms)  UPDATE "profiles" SET "updated_at" = $1, "activated_at" = $2 WHERE "profiles"."id" = $3  [["updated_at", "2020-08-23 17:32:46.239317"], ["activated_at", "2020-08-23 17:32:46.239317"], ["id", 11]]
   (5.8ms)  COMMIT
=> true
>> p.activated_at == p.updated_at
=> true

What's going on?