XF 2.0 Enable dynamic default avatars question

[Ozzy47]

As I understand this, when someone registers they get a colored avatar with the first letter of their username. So I am struggling to figure out how members can have a letter that is not in their username anywhere.

Such as these users in here.
https://xenforo.com/community/members/thetrailcamera.189048/ has a "D" as the letter for the avatar.
https://xenforo.com/community/members/foqqrrqrw.189058/ has a "I" as the letter for the avatar.

As you can see these members do not have the letter in their avatar anywhere in their username.

 

[Paul B]

They have set those manually.

 

[dethfire]

They have set those manually.

I was wondering this too as I have a recent example. Are they able to select a letter during registration or are you saying they uploaded a letter avatar with the exact style during registration? If so I find that highly unlikely, at least for my example.