New Videographer - Videos Getting Compressed too much

[LittleDende]

Hey, so I'm new to the art of video making, and I have a pretty decent camera - Sony AS50 - that shoots amazing quality videos. It can record in 1080p or 4k at up to 60fps. They look great when I play them back, either on my pc or my phone. As soon as I do any editing though, and then have to render the file into an uploadable format, it gets compressed down to about 200MB, and the picture quality is downright terrible.
Even when I didn't do any editing or converting before hand, and just uploaded the raw file straight to YouTube, the quality still came out really bad. :/
How does one upload a video without any loss of quality, and what file format should I be saving edited videos in to keep them looking beautiful??
Thanks so much!!

 

[HowToDudes]

What editing program do you use?

 

[LittleDende]

What editing program do you use?

Pitivi for Linux.

 

[Crown]

Moved to the recording / editing / production / hardware forum.