WoW players showed up during Sproutbringer, some stayed till Endwalker, and then most that still wanted WoW went back to WoW Dragonflight. Those that got sold 100% on the game stayed, but not sure if it was that much in the end (the game tends to create plot watchers rather than constant subscribers).
And if anyone is wondering what happened - the same thing as what happened during WoW Shadowlands - at some point people got so fed up with the game that it blew up. MMO playerbase always has some level of addictive relationship with the game and will not quit or even react when signs of bad content show up. The bad experiences have to pile up to create a reaction but when they do it will be on a much higher level, backend by emotions and the relationship nature of it.
Also, both MMOs (if not all in existence) have the same problem with expansions - they become a template and everyone gets used to a template while still expecting more. Devs want to innovate and prepare the game for the next 10 years, yet they are bound by the template - wherever it's planning, ideas pitching... Players want a cool new expansion yet they want to optimize, they want to get the best experience so they prepare based on the template, and if they get exactly that they may feel disappointed from their overoptimisation and also lack of surprises in the content. And when an MMO sneaks in something new outside of template walls not only does it have to be really good content but it has to fight against the template - like we got Island Sanctuary which got recked by an Excel sheet to then not rapidly react to players feedback - and in the end players requested more of templated solutions (which may or not be actually better, but players related to a known thing they liked which is pushing devs from trying out new things that are risky vs going for what was, is safer, but less exciting, less likely to grow the game).