Netflix’s ad tier blew its first candle last week, as the streaming megalith celebrated the anniversary with an overly cheerful blogpost that hid the disappointment over subscriber numbers that Faultline sensed from Netflix’s Q3 results last week. While Q3 profit and revenue were more than satisfactory for the streamer, ad-tier growth tells another story. There are only 15 million monthly active users (MAUs) of the ad plan worldwide, representing solely 6% of Netflix’s total 247 million subscriber base. The streaming service again did not provide subscriber numbers for the ad-supported tier. Of course, the Netflix ad tier is only available in 12 countries, but as a comparison, Fox’s free ad-supported streaming television (FAST) platform Tubi has over 70 million MAUs,…