Whenever I try to upload this image it gets all blurry https://apocalyptichead.blogspot.com/2024/03/romantically-apocalyptic-2010-147.html (yeah, the original file does not look like that) and it's weird because I've posted long strips before and it worked fine https://apocalyptichead.blogspot.com/2022/11/romantically-apocalyptic-2010-88.html
1/2:
Uploading isn't the issue. It's the way the image is being displayed that is the problem. You need to ensure that you set it to "original" size. I just downloaded your full size version and uploaded it to my own blog: no problem at all.
Take a look. Here is the image uploaded just in the normal way on the top (which is "large" size). Below that is the exact same image inserted from Blogger's archive (since, after that first upload, it's already stored) but I tapped the size icon to change it to "original". You can see how huge it is. I had to zoom way out on the post editor just to show you:
So you don't need to reupload anything. Just insert the image again, and choose "original" once it's in the post.
For some reason, the second link is embedding the image in your post in what seems to be its original resolution. The first link, however, is embedding a version of it that is "scaled" to Blogger's "large" size.
Look at the differences in the embedded urls:
/s1600/Romantically%20Apocalyptic%20%23147.jpg
vs.
w621-h4056/Romantically%20Apocalyptic%20%2388.jpg
My guess would be that when you made those blog posts, in the post editor you uploaded the images (which displayed natively as "large" size) but for your second link (the one that is looking right) you probably clicked it and chose "original size" as an override. Try doing that in the post editor for the other one too. Should be fine after that.