Another thing to remember and something you have alluded to is runway width, thinner runway, to what your used to, will make it look like you are higher than you are so you flare late, a wider one makes you think you are lower so you flare early.
With the landing it was flat and that's that.
So if you are landing on a lake on floats or on a large flat area of snow on skis how do you judge height for the flare?
You were probably looking in the wrong place !
Cast your eyes at the far end of the runway and it may never happen again .
Of all the advice in how to judge height when flaring this has to be the very worst.
It started about thirty years ago in the flight training industry and was embraced as practical and safe by the industry and since then has become the norm.
No wonder pilots have problems judging flare height.