wordpress-activitypub: Release v1.0.0 breaks existing profile pictures

Quick summary

Since the update to version 1.0.0, my profile picture has been replaced by the Gravatar logo

Steps to reproduce

1. Use version 0.17.0, see how profile picture works
2. Update to 1.0.0, see how profile picture was replaced by Gravatar logo

• See additional notes

What you expected to happen

To see my profile picture.

What actually happened

Gravatar logo is shown.

Impact

One

Available workarounds?

No but the platform is still usable

Logs or notes

I created my own plugin to generate avatars locally, which uses the get_avatar filter. It returns an img tag, with a data:image as source. This works well in WordPress itself, and also worked fine in ActivityPub version 0.17.0, so something must have changed in 1.0.0 which breaks the compatibility.