We are running a small experiment where 0.3% of viewers will see an auto-generated thumbnail, instead of your custom thumbnail. We are not removing the ability to create your custom thumbnail, but we hope to gain insights on auto-generated thumbnails for the future.
one time i made my own thumbnail for a video and youtube's auto-thumbnail generator gave me the perfect freeze frame facial expression for a clickbait video so idk mang

I do GB Studio music commissions! 
DM me for deets!