Best way to export 4k iPhone footage

I am a content creator and use my iPhone to film cooking videos. I've recently run into trouble, where my content exported at a lower resolution than it should be. After some digging, it appears that I was downloading footage from my iCloud folders, which stores the footage at a much lower quality.

Once I discovered this (and spent hours editing the footage), I decided to import all of my content directly from my iPhone, via USB. When I tried, I noticed that a good bulk of my content was missing from my iPhone input in both Apple Photo and Image Capture. I suspect that because I am connected to iCloud, that only lower resolution versions of these videos are available.

What is the best way for me to find and download the original, 4k files of these videos? Separately, if I turn off iCloud, do I run the risk of losing the permanent version of those photos forever? My iCloud has been downloading the originals for days now, with no progress.

I just want to download these photos to my computer so I can edit them! I feel like this has become so much more complicated than it needs to be. GREATLY APPRECIATE YOUR HELP!!!