https://forum.doom9.org/showthread.php?t=154533
1280x720x50.000p / 59.94p is perfectly legal on BD, commandline suggestions are there and I am using this regularily if 25i/29,97i sources come in and optical discs are wanted.
Only if source is really worth 1920x1080, well then... Bust most are not, downsizing from the usual 1440x1080 HDV cam with CCD means no real loss in detail, even from most 1920x1080 HDV cams.
And I suggest to keep your sources anyway.
I would expect that with the advent of AI resizing interlaced SD/HD/FHD sources can be upconverted to double framerate AND uprezzed
even more convincing as with QTGMC now, as much as I like it still, and for the last 10 years.
One more year and we are there.