Upload Speed being throttled

Curious if anyone else is having this issue. This was about 2 hours of extensive testing to see what's going on. I've been backing up my hard drive to google. It's about 400gb. With a frustratingly slow 20mbps upload (and no real way to upgrade it unless I quintuple how much i'm paying right now), it takes a few days running constantly.

Each one of these actions, I did a speed test (after pausing the sync), which came back .09mbps.

On day 2, I noticed a near 0 upload speed. I paused the sync, restarted. No improvement.

I paused the sync, quit the program, and restarted. No improvement.

I paused the sync, restarted the computer, and restarted the upload. No improvement.

I unplugged and restarted the modem. No improvement.

I checked my phone upload speed. Shockingly, 23 mpbs. I checked my laptop upload speed. Shockingly, 23 mbps.

I paused the syn for about an hour. The mpbs crawled up to 8mbps on my desktop. Phone and laptop still showing 23. But, the second I restarted the sync, it went back down to 0.

Okay, so here's where things get dark quickly. I go to the xfinity website, and do a speed test there. My upload speed shoots back up to 23 mbps! Then, I do another google speed test! The same!
But, 5 minutes later, back down to .09mbps on my desktop (laptop and phone still showing 23mpbs).

I repeat the xfinity test several more times. Each time the xfinity test shows a 23mpbs ul speed. This entire time, my download speed has NOT been affected at all. It's just my upload speed, and just on the device that's using it.

So, I let it run all night. It uploaded, just very slowly. And it's still throttled in the morning. 

A few notes. I checked my task manager, and nothing was uploading in the background. Also, I checked to see if my plan has a data cap. It does not.

It's clear with these tests that comcast, rebranded as xfinity, is throttling my upload speed on a specific device.