I haven’t made any wallpapers in a long time, but I wanted some new gradients and no one had seemed to make any that totally made me happy, so I made my own. I hope you enjoy! Update 2019-08-26: I've added 4k desktop/iPad versions at the bottom of this post. They're big files, but gradients are wildly inefficient when it comes to compression.
As always, these are at 4k resolution and you should click the links to download each one directly (WordPress will downscale the ones you see on this page).