Abbreviated subscriber count

YouTube has displayed rounded public subscriber counts since 2019. Below a thousand the figure is exact. From a thousand up it shows three leading digits, so 1,234 reads as 1.23K, 12,345 reads as 12.3K, and a channel on 133,017 sits at 133K until it reaches 134,000.

The rounding applies everywhere the public can see it, the API included, which is why third-party trackers move in steps rather than smoothly. Your own exact figure lives in Studio analytics and updates continuously. This is the answer to the complaint that a count has not moved all week. It has moved. The display simply has not caught up with it yet.