For me, it was APImageddon - when Christian of Apollo played out the whole story, the lies he had been told, and how he tried to negotiate and Reddit just wouldn’t budge; when he said that there was no way he could make it work, I said, “Well, looks like I’m done with Reddit.” I went to mastadon first, but I’m not a micro-blog person, so I went between Kbin and Lemmy.world. I went to Reddit a few times, spreading the word and looking for communities that made the migration but, for the most part, I didn’t look back. I tried to contribute, and when it was quiet, I touched grass and stuff. I’m now at Midwest.social now because of the piracy debacle and .world defederating with Hexbear. I still use my mastadon account from time to time. But I’m happy and only see Reddit when it shows up in searches.
Edit: I did go back Reddit to help make pixel placing canvas (what was that thing called again?) a very special send off though. Fuck spez 4ever!