Sequoia QuickTime Player plays middle part of high frame rate movies (seems to be ≈85 fps or more) in slow-motion.
That can be prevented by adding or editing FullFrameRatePlaybackIntent tag to value 1 with:
exiftool -m -P -overwrite_original -ext mov -Keys:FullFrameRatePlaybackIntent=1 movie.mov
exiftool -a -G1 -s -n -FullFrameRatePlaybackIntent -VideoFrameRate movie.mov
[Keys] FullFrameRatePlaybackIntent : 1
[Track1] VideoFrameRate : 239.969738998865
Or by playing such movie with Sequoia QuickLook or some app like IINA that does not honor that tag. Then the whole high frame rate movie is played in normal speed (if the device can handle that).
That tag can be set back to the "middle part slow-motion" option with:
exiftool -m -P -overwrite_original -ext mov -Keys:FullFrameRatePlaybackIntent=0 movie.mov
Or deleting that tag with:
exiftool -m -P -overwrite_original -ext mov -Keys:FullFrameRatePlaybackIntent= movie.mov
But Sequoia Photos.app plays the middle part of high frame rate movies in slow motion no matter what.
So for Photos those movies must be re-encoded at a slower frame rate. So export such movie as original out from Photos and re-encode with some 3rd party app. 30 fps is a good starting point because it is an even integer of 240.
For example with ffmpeg H.265 defaults and '-r 30' for 30 fps with something like (this preserves metadata date but other metadata must be copied from the original which is best done with exiftool -- ffmpeg versions 4-8 do not properly handle movie metadata):
ffmpeg -i input.mov -c:v libx265 -r 30 -crf 28 -preset medium -timecode 00:00:00:00 -tag:v hvc1 -map_metadata 0 -c:a copy output.mp4
Handbrake does about the same with its default setting (maybe force 30 fps via Video tab > Framerate > 30, Constant framerate).
