You should know that Tumblr disabled the ability to access high-res images about 2 weeks ago. For images, the pixel limit is 1280 width and 1920 height. Take this post for example and its standard image link: https://78.media.tumblr.com/a308352.....h5eo2_1280.png

This gives you an image size of 1280x1761. If you changed the "1280" to "raw" and changed "78.media" to "data", you'd get the full image size of 4518x6215. Tumblr decided to scrap this for reasons they won't disclose, which means we've practically gone from glorious 4K back to 720p. Lots of large vertical comic strips are almost unreadable unless a link to a better site is posted. What's the point of a site that's mostly used for art if all the high-resolution pictures are shrunk down with no way of viewing the full size? I don't know if Tumblr will listen if their users make noise about it, but it's worth a shot. Contact support and explain how disappointing their decision is. Make blog posts on Tumblr and other sites. Do whatever you can to make the situation known.