White/corrupt thumbnails on recipient side if sender blocks Canvas data extraction

Some Canvas features can be used for fingerprinting and are therefore disabled by some users. For thumbnails to work you need to allow Canvas Data Extraction on the sender side for thumbnails to work on the recipient side.

Sender side thumbnails work in either case.

From what I heard from someone I was talking to about this just now the recipient side downloads the image regardless of if it's clicked or not, making most of the point of sending a thumbnail moot and means the thumbnail should be generated on the receiving side so them working isn't dependent on the sender.

Riot 1.2.2.

[turt2live]

I wonder if this is the cause of #8333

@bwindels were you ever able to get to the bottom of your thumbnail issues? (and are you still having them?)

[bwindels]

No, and yes. Sounds plausible!