Currently, public sub counts are abbreviated in most but not all places across YouTube. In August, we’ll make this more consistent by always showing abbreviated sub counts publicly. Creators: You’ll still see your full sub count in Studio! Learn more → http://yt.be/help/abbrev-count …pic.twitter.com/pmaKk4EU4k
Hot take: 15,438,843 subscribers rounded down 15M isn't bad. 7,234,384 subscribers rounded down to 7,2M isn't that bad either, but might feel like it. Why? We're talking about sizes of countries with millions of people. Those numbers are HUGE.