Some small amount is expected. For example, if it happens across samples, disliking and then changing it to a like would be counted. Or, like you suggest, if it

Some small amount is expected. For example, if it happens across samples, disliking and then changing it to a like would be counted. Or, like you suggest, if it's clear that it was done by a bot, it could be OK for Google to remove it, and it wouldn't be meaningful. But could that ever explain 95% of the downvotes being hidden?