Destiny 2 doesn’t cap XP earnings - they get reduced by up to 95%

Update, November 23: An extensive look at Destiny 2’s XP systems reveal what’s actually going on when your earnings slow down.

We’ve been hearing that Destiny 2 has implemented a cap on experience gain for some time now, but it turns out that’s not really the case. Instead, you can keep gaining XP for as long as you want - it just eventually drops to around 4% of the normal rate.

Conquer the endgame with our Destiny 2 leveling guide.

That’s according to an exhaustive report from Redditor EnergiserX, who has graphed out XP gain in a wide array of settings. Essentially, it’s argued that the game drops XP as normal if you’re playing slowly, reduces the rate by 50% if you’re playing normally, and drops by as much as 95% if you’re power-grinding.

Perhaps the most notable example of the scaling in action is that you can never actually earn the full experience awarded by a public event, since the XP at the end is enough alone to trigger a 50% scale back.

from
https://www.pcgamesn.com/destiny-2/destiny-2-xp-cooldown-cap-clarion-call