A find from Problems (2012 puzzle)

On the bottom right of the Problems image (https://i.imgur.com/8D7hN.jpg) from the 2012 subreddit, the following text can be found: www.easystereogrambuilder.com. This was most likely the website used to create the image. (credit: geomatria)
Here is a closer + better look at it: https://imgur.com/a/8p22f57 (credit: taiiwo) - "For clarity... I isolated the watermark using gimp by taking the images without the watermark from the left side of the image, moving them pixel perfect over the bottom right side, ontop of the images where the watermark is, and using the "Grain extract" filter to subtract differing pixels. The grey and noise in the image is due to the jpeg compression"
A stereogram, according to brainbashers.com is "a picture within a picture. Hidden inside each image is an object which appears in 3D when viewed correctly." The site also links to this wikipedia article on how to view them correctly: https://en.wikipedia.org/wiki/Autostereogram#Viewing_techniques
The original image used was a narrow version (borders brought closer) of a medieval tapestry of king arthur made in belgium (https://imgur.com/a/zOu3dEb)
Somebody looked into it a tiny bit here: https://eli40.com/rights/cicada/04-reddit/

*This most likely isn't important for solving LP, just a cool find