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
https://support.google.com/youtube/thread/6543166?msgid=6544425 … “Who asked for this? I haven't heard anyone clamoring for consistency on this, and this seems to be a net negative for viewers, because they might have less trust that "4.2K" is real than "4,227".”