Also, no company's success should ever depend on alienating its users and slandering longtime contributors.
the parallel for traditional companies is choosing to bust unions, and a month before you IPO is an absolutely terrible time to choose to bust your union unless you're absolutely 100% sure you're immune to a "strike".
in this case it's not just picking a fight with powerful stakeholders (like mods) but also turning off features that a ton of users interact with the platform via, and trying to force everyone off third-party clients onto the new experience and native app. In this model the users are a stakeholder that you're picking a fight with at the same time.
the best time to do it is 20 years ago, but, a month before you IPO is not the right time at all.