gravatar,initials doesn't fallback when gravatar.com is unreachable

[jdow]

Describe the bug
On System -> Settings -> Avatar section, there is this blurb of text:
Multiple values can be set, comma-separated, and authentik will fallback to the next mode when no avatar could be found. For example, setting this to gravatar,initials will attempt to get an avatar from Gravatar, and if the user has not configured on there, it will fallback to a generated avatar.

However, if authentik is deployed in an environment that doesn't allow a network connection to gravatar.com, i.e. firewall or similar, even the setting "gravatar,initials" leaves each user's avatar as a broken thumbnail, and initials are never retrieved. Further, each GET of a user ends up being really slow. i.e. retrieving 150k users by paginating through /core/users/ takes 12 hours.

Once changing the setting to "initials" only, retrieving 150k users takes about 2 minutes, and users have proper initials avatars.

To Reproduce
Set global Avatar setting to gravatar,initials and block outgoing connections to gravatar.com

Expected behavior
Failback to using initials setting

Version and Deployment (please complete the following information):

• authentik version: [e.g. 2024.2.2]
• Deployment: [e.g. custom helm]