I definitely think outside competition is a factor. There is just more churn in general for content creator and regular gamers.I imagine some of the drop-off is just due to outside competition and not Necropolis-specific.
Last Epoch - Feb 22, 2024
No Rest for the Wicked - April 19, 2024
Hades II (EA) - May 7, 2024
Those are all games that I could see resulting in some Path of Exile players taking a break to try the new hotness. Like I'm starting to get bored of my current build and I'm tempted to play one of those new games rather than reroll a new character.
I'm also guessing I'm not the only Action/RPG player who has been replaying Elden Ring because of the DLC coming out soon.
I was also into Dragon's Dogma 2 while the PoE league was out.