I am trying to use google photos as my wallpaper (I have done so in the past), but I keep getting an error when trying to set the settings. I am unable to see anyone of my pictures or albumns. I tried logging out of google photos and loggin back in, but once I log in, it says....

An error has occurred.
The remote server returned an error: (400) Bad Request.
Status: ProtocolError

Content Length: -1
Status Code: BadRequest
Status Description: Bad Request
Response URL: https://picasaweb.google.com/data/feed/api/user/default?kind=album

https://picasaweb.google.com/data/feed/api/user/default?kind=album

Am I doing something wrong, or is it broke?

Same here.

https://picasaweb.google.com/data/feed/api/user/default?kind=album
Returns:
The Picasa API is deprecated. See https://developers.google.com/picasa-web/ for more details and the migration guide.