Excellent = 4K. You will only see this on the CCU.
Also it's not surprising that 1080p looks blurry when upscaled to a 1440p display. On a FHD display the 1080p60 stream looks quite nice.
Oh, wasn't clear for me that you will only see excellent when using CCU. I thought this is just a connection Info about what is possible. Thanks for this info.
Anyway - on my Lenovo its changing between "ok" and "good" while it runs better on my macbook.
And yes - you are right. on 4k it looks blurry and this is absolutely normal. I'm still waiting for 3440x1440 support.