iPhone HEVC and HDR footage
Recent iPhones can record efficient HEVC video, high frame rates and HDR inside MOV. The file may already be compressed efficiently even when it is large. Converting it to H.264 MP4 improves compatibility, but matching the original visual quality can require more bitrate because H.264 is older. Check bright highlights, skin tones and gradients after conversion because HDR to standard dynamic range handling can matter more than the final byte count.