Video quality and exporting

Hello,

I am new to filmmaking and editing and exporting. I am trying to film and put together fun home videos of my kids that I can hopefully cherish forever. I want to put together a nice high quality video with nice edits for myself and my family later in life. I put them on YouTube and set them as private so only my family and I can view them. I do that manly for a backup storage option. So here is my set up. I have a GoPro hero 8 that I mostly film in 2.7k 30fps, also sometimes shoots in 4K 30, and randomly shoot in 1080p. I also have a dji mavic air 2 that I shoot in 4K 30. All videos look nice once I upload them to my iPad. I export my videos from my GoPro and drone directly to my iPad Pro ( latest model ). My videos then go to my files. I then upload my high quality videos to primiere rush and they do not look like the high quality  videos they once were. I then export and it then looks even worse. When I upload them to YouTube they are still not high quality.  My question is what am I doing wrong? Any help would be greatly appreciated. Thanks.