Why is my upload so much slower than what it should be and how can i fix this?

I go to https://www.speedtest.net and it says my upload speed is 20 MBps but when I go to upload files to Google Drive and look in task manager it's only uploading 1.5 MBps. I tested with both the client and browser and both are the same upload speed.

I don't know anything at all how upload works so I'm in hopes to find out a way to increase the speed. I need to upload 800 GB of data ASAP but that is taking forever.