Destiny 2 has had a rough year, after an intense, rough couple of weeks involving layoffs and revelations about the health of the game and the company. A lot of factors have combined to produce a new playercount low, at least from the metrics we can track.
Judging by Steam numbers, a significant portion of the playerbase, in the last 30 days the games average playercount was 34,816 and its peak playercount was 59,076. Those are both all-time lows, ever since the game was first released on Steam.
Source: N4G PC Destiny 2 Has Hit Its Lowest Player Count In Franchise History