Ijs 
Discussion
Yes it is. It is condensation.
This is normal.
Cars do the same thing on the ground in the arctic in super cold temps.
Also if these were spraying chemicals do you know how many pilots and ground crews would have made tik tok videos to expose this?
It’s not chemical trails.
Show me a picture of a jet with sprayers! They don’t exist.
Crop dusters don’t count.
Cold and warm pockets of air.
The atmosphere has all kinds of “layers” and “rivers” of air. Density and temperature vary. (The ocean has these layers and rivers too.) that’s was caused turbulence when flying.
That video of CONTRAILS appearing and disappearing is not uncommon.
Take a basic earth science class.
Now in some areas, where skiing is a big industry, cloud seeding is a thing to foster a heavier snowfall. But conditions must be just right and of course they only do it when necessary. Crop dusters are used to spray silver iodide and dioxide for this.
Come on dude. Some conspiracy theories are real, but not this one. Engage your critical thinking skills.
So which ones are real? Many things I learned in “class” as a child have been lies uncovered as an adult.