I've just made a video how it is flickering on my Forma. It is made by Samsung Galaxy Note 8 in slow-motion mode.
Forma is flickering
As you can see Kindle Oasis 1 does not have that flickering at all, but Forma has it from 7% to 100% except 67% for some reason.
But I can't say it is somehow bothering me, most of time I read without front light at all or on very low level about 4-5%. And I can't see it without filming at all at any level.