We constantly validate the likes/dislikes on a video and only show the count we believe to be valid. Here more info: https://goo.gl/TM6pTM . Hope this helps.
@TeamYouTube brought this up a while back when it happened months ago and it's still happening, the likes on my videos will be high and then suddenly drop to lower numbers, but the number in creator studio never changes/updates, why are 50-100 likes being removed from my videos?pic.twitter.com/Z9DbGTuTkG
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Thanks. Twitter will use this to make your timeline better. UndoUndo
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Self made man 
Penguin King
Youtuber & Twitch streamer
went to the HDWGHT: 3/11/18 