Read The security risk of embedding images from external sites by Jan-Lukas Else (jlelse.blog)

On a lot of IndieWeb sites, I noticed that profile images of webmentions get directly embedded from their original source. For example, Twitter profile images are loaded directly from Twitter servers (pbs.twimg.com) or even my profile image is directly embedded from my site. However you should consi...

Definitely an interesting point to work on. Generally I find that embedding images from sites like Twitter also becomes a UI problem because people changing their avatars over time means that avatars disappear.