The problem with uploading 1080p videos to YT is their conversion allocates a pretty low bitrate to 1080p. They only give 1/3 to 1/4 the bitrate to 1080p they give to 1440p, despite 1080p being over half the pixels (.56). It doesn't matter if you give it high bitrate when compressing before uploading either, as YouTube will not make use of it.
You used to be able to use a trick to slightly resize the video to 2048x1152 to trick YouTube into using the higher bitrate it allocates to 1440p, but that doesn't work anymore. However you can still get them to look noticeably better by resizing them to actual 1440p (2560x1440). However you need to use more bitrate when compressing.
I was reluctant to try this due to thinking the loss of pixels would make it much blurrier, but YouTube's 3 to 4 times the bitrate for 1440p upon converting them more than makes up for it. I use Avidemux to edit, compress, and resize. It also has a ABR (Average Bitrate) option, which is far superior to VBR (Variable Bitrate), or CBT (Constant Bitrate). If you want to try Avidemux and need help, I can guide you through it, it's relatively easy though.
ABR uses a two pass compression method, the first pass analyzes where to place most of the bitrate by detecting motion. The second pass compresses the file. YouTube recommends 30,000 bitrate for 1440p content, but I have found that is only necessary for very high detailed games. For instance Ghost Recon Wildlands has lots of ground foliage that can look blurry when traveling over it, whereas The Evil Within is slower paced with less graphic detail.
Here are examples of GRW with both 1080p and 1440p uploads, and TEW with 1440p. All were captured in 1080p. The bitrate is 30,000 for the 1440p GRW vid, and 20,000 for the 1440p TEW vid. The differences will be most obvious when viewed fullscreen.
1080p GRW Upload (select 1080p view option)
1440p GRW Upload (select 1440p view option)
1440p TEW Upload (select 1440p view option)
I really don't get why this thread was labeled [Solved], I see no solution presented.