As far as I can tell, the timeline is

1) Reddit announces publically that they will not be doing a twitter-style shutting down of 3p apps, that they are very pro 3p app unlike evil Twitter (was at least how I read the subtext)

2) Apollo dev feels secure, doubles down on growing his app. accepts invites to speak at apple developer conference just a few weeks ago, for instance.

3) Reddit drastically increases API prices in a way that makes free 3p apps impossible. All reddit third party apps now have 4 weeks to convert their business model from free-with-paid-extras to mandatory-subscription-for-all. Of the 8 or so 3p apps, every single one decides that this is impossible and that they must instead shut down their projects. Even the ones which are, for instance, about giving blind people access to reddit, or the ones which are basically apps for accessing specific subreddits and which have extremely passionate, extremely small user bases. Afaict, not a single developer decides to try to ride out these changes; all of them instead shut down. (if anyone can find an app that is actually trying to make the transition, let me know; i at least couldn't find one, and i looked pretty desperately)

4) Obviously this involves making a post explaining to their respective communities that they are shutting down the project. All of them explain why, including estimated price calculations and basically just explaining that maybe there would be a path forward but they just don't have time. Some emphasize how much it would cost for all of their free users API access, others emphasize how difficult it is to transition from free-with-paid-perks to a subscription-for-all model. Apollo is one of the former. It feels mostly like they are justifying themselves to their disappointed userbase, preempting comments of the "how dare you take away my only way of accessing reddit!" variety. It would frankly be very strange if they didn't do this. All the posts are professionalish, lots of strained "we want to thank reddit for making the platform we worked with for so long" style stuff

5) u/spez, the CEO of reddit, shows up in the comments in Apollo's goodbye post, and only Apollo's goodbye post, acting hostile and with an accusatory undertone. It feels very strange and out-of-place, and people say so. Spez gets defensive and starts badmouthing Apollo dev, calling him unprofessional and hard to work with. This then devolves into a back-and-forth between Apollo dev and u/spez, with 2 main plot points:
a) apollo dev makes the jokey point that, if reddit's costs from apollo's api usage were really $20m, then shuttering Apollo is gaining reddit $20m, and perhaps half of that benefit should accrue to him. This is after the point where both of them had started being sarcastic at each other, and it was pretty much impossible not to read this as a mean-spirited joke expressing skepticism that these numbers weren't exaggerated. But u/spez seemed to take it absolutely seriously and treat it as a serious request for reddit to mail apollo a check for $10 million dollars. they have a really awkward thread about this where it's obvious u/spez understands the joke but, idk it's weird, it feels like he's desperate to get some debate points for apollo dev demanding money from reddit for no reason, and so pretends like he doesn't get the joke. While reading it I got deja vu of watching vinay gupta take deiseach's mean-spirited jokes absurdly seriously for the same reason in that one SSC post about buddhism. it was cringey to read and made u/spez seem like a narcissist. which segues nicely into plot point #2:
b) the whole phone call thing. After spez had already attacked the Apollo dev, I get the impression he kind of realized like, "wait, why am i trying to be professional with this guy who is slinging crap at me, now that apollo is dead i'm just another shitposter" and decides to post the transcript of the phone call he had with reddit where they repeatedly told him he had nothing to worry about and they weren't going to pull a twitter and they supported their 3rd party devs and such, going through the specific lies and asking u/spez to comment on them

frankly the apollo dev's behavior seems totally justified. All of the hysterics are based on the CEO of Reddit coming into Apollo's goodbye post and commenting some extremely bizarre and hostile stuff, something he didn't do to any of the other extremely similar posts for the other apps. It really does seem like he has a grudge against Apollo and its developer, and the Apollo team didn't start swinging until they had already taken a few hits in the thread.