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.
Wait so, you don't allow people to make custom thumbnails until they build a fanbase/subs, but when they build a fanbase to make said custom thumbnails you run experiments where those thumbnails won't show up???? What kind of doofenschmirtz level of company are you running?