Even though YouTube specifically allows you to hide your Channels subscriber count. Everybody makes the subscriber count visible to the public. This will give some hype to the channel.
Third parties who use YouTube API Services will be limited to the truncated subscription count. This can affect many apps and websites who rely on these services mainly.
Those channel with less than 1000 subscribers won't be affected by this new update. Their subscriber count figures will be shown correctly.
YouTube doesn't really say why they are truncating subscriber count. But they do say they want to create more consistency everywhere.
Example of how the abbreviation is done:
- A channel with less than 1000 subscribers will be shown accurately.
- A channel with 4,352 subscribers will be shown as 4.3K subscribers.
- A channel with 7,237,932 subscribers will be shown as 7.2M subscribers.
- A channel with 15,423,672 subscribers will be shown as 15M subscribers.
This update is going to happen in August 2019. To create consistency everywhere, this feature will be roll out to YouTube apps and YouTube.com and to YouTube API Services.