I left during the API kerfuffle even though I didn't use an app. I had been thinking about getting off of it for some time prior to that because I realized doomscrolling was negatively affecting my mental health. So I followed the refugees from /r/DaystromInstitute to startrek.website.
Article 5 doesn't oblige members to take any particular action. It only says that an attack on one is an attack on all, and leaves it to each member to decide what actions, if any, they will take in response.
I could fit if I didn't have these damned arms!