I've had a screenshot of the original The Sniler post on Tumblr saved with other notable media for a little while, but it had not occurred to me to research the origins of the image until I have encountered another photo (image 1) and thought "Wait a minute, that's the cat".
Direct image search for either hasn't been particularly fruitful (mostly memes), but it did bring up a Pinterest result with another photo (image 2) among the "similar images" that had the same blanket backdrop as the original and a watermark in a corner.
From there I found that the number (954459180) is the ID of the owner on RED/Xiaohongshu, which is a Chinese Instagram-like social media.
Just like with regular Instagram, you can't do a whole lot on RED without registering, but I did find two dozen more photos of The Sniler uploaded on Facebook.
So there you have it
&BTW.... THE SNILLY