In addition, Opensea does not show any of the thumbnails correctly, even refreshing the metadata. However, at Rarible all my domains show the current ENS image or the avatar I set to make some tests:
If you were to refresh the metadata on the older colorful backgrounds, it will show the new blue background. The ENS names that have these older colors is something OS generated I think, and they update to the new standard blue on a metadata refresh. However, that might be up in the air if OS is still having trouble showing the content.
These are both on Rarible. For some reason their search isn’t updating. You might want to open a ticket with them. Not sure if they have a “refresh metadata” option there.
I’m not quite sure why Rarible does not have the options to refresh the metadata. You might want to open a ticket with them and see if they can assist. Their help center is located here: https://rariblecom.zendesk.com/hc/en-us
On rarible.com in the footer the Help Center link goes to zendesk.