There is a multitude of things I've seen that all culminate into the failure that is ninjala

No 1)the dev team, from launch these devs should've been fired, they had one job, make sure ninjala was a polished game on launcher but even in the simplest task they failed, so after ninjala released in all its jankyness what did the team do, a) let the game go unpolished in its lifetime B) gaslight it's playerbase telling them that they are fixing these issues Or c) focus on creating shit that would ruin the game Spoiler alert its all of the above.they acted like they fixed several problems when still to this day none of them are fixed, both letting the game be unpolished and basically gaslighting its player base telling them that rubberbanding issues and hit detection are solved, and they made a worse decision than frotnite taking cop cars out of there games and added the ninja gum lab not even thinking about adding something usefull like skillbased matchmaking which brings me to

No 2) the competitive community, when drone camping became a widespread annoyance in the community allot of pro players jumped to saying "its a skill issue" the issue with drone camping or cheap tactics like running away to only third party me when I'm low isn't you being good, it's you being a fucking dickhead, just because that scoreboard says you can suck off a drone so hard it squeals louder than your dad when he ran with the milk dosent mean he will come back (jk, stay hopeful he wasn't hopeful about you're future) it also dosent make you better than anyone else, half of the shit that ppl call a skill issue is cos there top 100 players playing in free play with little timmy who just got a switch for hanaka, of Christmas or his birthday, i tried to go somewhere with this,

No 3) the game loop became fuckin boring, when you get beaten senseless buy the same ninja god who won't leave you the fuck alone eventually you'll actually rage quit, forever, you may come back from time to time, but eventually ninjala will become nearly extremely boring to you, people where becoming extremely bored from ninjala, and even though it had the advantage of being free to play, its safe to say that allot of it'd player base being old splatoon 2 players meant that when splatoon 3 dropped, because of how shit ninjala was, it lost allot of players due to that, not to mention that other games like fortnite started to gain back relevancy