I wouldn't say I'm more active in terms of posting and commenting, though I wasn't too active on Reddit the last few years to begin with. Though the fact I haven't logged into my Reddit account of 10 years since checking out Lemmy speaks to how at-home I feel here, even after basically giving up one of the sites I used the most in the past decade or so.
The API change fiasco and the fallout from it was definitely the straw that broke the camel's back for me, but if I'm being completely honest all the other missteps and fuck-ups from the company were pushing me closer and closer to finding an alternative for years. I stayed for as long as I did mainly because it was a good place to get news and interact with various niche communities, but really Lemmy does all of that just as well, for the most part.
That said though, I don't think I would've been as ready to leave Reddit were it not for Elon buying Twitter and absolutely fucking that up too. That was the main thing that got me to look into alternative social media sites in the first place, though I haven't been as fruitful with finding a good Twitter replacement yet.