Recently Dogenzaka pointed out that you can get the raw image from a Tumblr post by reblogging it and exporting your Tumblr. This method has been added to howto:sites_and_sources#tumblr. I used it to update post #1732714, post #1732723 and post #1732729.

There are a lot more posts in source:tumblr width:1280 date:2018-08-01..2018-12-31 that could be updated, but it's hard to tell which posts have been downscaled. post #1652551 had a width of 1280, which suggested it was downscaled and it was. But post #1689980 also has a width of 1280 and the raw version is no bigger. Does anyone know how to tell which posts have been downscaled?