the only thing that will remove it is sublimation.
And that happens fairly quickly. Many years ago, I had the misfortune to on board an aircraft (as a passenger) that departed with a lot of ice and rime on the wings, and it was all gone (due to sublimation) before we reached cruise level.
If you fly the 737 and you pick up ice during climb out, what is left on the outer slats (not heated) after you use the wing deice, will also be gone rather fast.
I'm not saying it's fake, but it doesn't look right to me.
FL650 was just a number, but it looks like a lot higher than the usual 350-370. My opinion.