Inconsistent handling of attributes with _ during enrollment

[TommyTran732]

Describe the bug
On my enrollment form, I have 2 prompts with these field keys

• attributes.standard_auth (Order: 2)
• attributes.passwordless_auth (Order: 3)

After the user has been enrolled, they end up with the following attributes:

settings:
  locale: ""
standard:
  auth: Yes
standard_auth: Yes
passwordless_auth: No

Expected behavior

The following section should not be added to the list of attributes:

standard:
  auth: Yes

Additional context:

If I use the following field keys, it works properly:

• attributes.standard-auth (Order: 2)
• attributes.passwordless-auth (Order: 3)

The bug is only reproducible if the field key contains "_".

• authentik version: 2025.8.3
• Deployment: docker-compose