[Bug] Saving display name after edit does not do anything

Hi!

When saving the display name after editing it, it does not do anything except for showing a blank "Edit Profile" page.
Editing the display name does work in the web UI, the instance I'm on is `pixelfed.social`.

I'm on Pixelix version `4.3.3`!

<img width="763" height="1512" alt="Image" src="https://github.com/user-attachments/assets/62bb0590-0e73-46e9-8b7a-5d38702fe47e" />