Export bad quality when uploading to social media??

Hey guys,

(Included 2 images in this post so you can see quality differences in the original file and YouTube) 

So I have some GoPro footage edited of about 7 minutes and when exporting looking at the file itself on the computer it looks great... sending it over to my phone in the original format looks great to... however when I upload it to instagram or youtube the smoothness of the video goes away and it starts to look all grainy and a little blurry. mind you there is allot of movement going on and FYI some things to know:

- My edit contains footage from my GoPro mixed with 1080p, 4K, 2K and 240fps, 60fps clips and my edit has some images in it, also a few clips from my iphone and some screen recordings from my iphone.

- 80% of my clips are 1080p 60 fps, about 4 clips are actually 4K and 2 are 2K and about 5 clips are 1080p 240fps

- My final export is 1080p 59,94fps 

- I have messed around with the bitrate and tried exporting 15mps 2vbr and 65mps 2vbr both have the

same outcome when uploaded on social media. 

- I tried exporting it as 4K, same outcome.

- Render at maximum depth is on.

- Profile = high.

- Level: 5.1 

- Main platforms I want it on are: YouTube and Instagram. 

So yeah like I said the exported file itself looks great, even in the preview panel in premiere on 1/2 it looks great... it's only when I upload it that it looks bad. and it makes me feel like I have done all this work for nothing! 

So if anyone has some tips please let me know! maybe I'm just not seeing something or doing something wrong. 

Thanks.