I guess this happens for edited high quality images as well.....
I recently contacted Apple support and they confirmed:
If you download your photos from the iCloud website to your PC, you can currently only download photos/videos in jpeg/mp4 format if you click on the photo/video one at at time and manually click the download "most compatible" option.
If you try to select and download more than 1 item at once (where it will download in a zip file), no matter which download option you choose, the files will download in HEIC/MOV format, and be uncompressed. This was not the case 1 week ago, downloading up to 1000 items in the format you wanted was no problem.
Apple updated their iCloud website a week ago and this bug has yet to be fixed. It may not be the best way to pull photos from an iPhone to your PC to have personal copies but up until last week, it was at least reliable.
For reference a 4min 30sec video recorded in 4k60 hdr on an iphone 13 pro is over 3GB in mov format but downloads in mp4 format at just above 120MB.