The downtime also starts happening in 2020, which is a while after the acquisition. 2020 was the year many people started learning to code while being stuck at home.
After Microsoft acquired them, they started rolling out new features at an incredible pace. And if you look at the breakdown of the downtime, most of the downtime is in features that didn't exist before the acquisition.
Though not all of the downtime is in new features. The core is also less stable than ever.
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[1] Possibly none, are you paying for a pro or enterprise account?
[2] There will be a little indirect income perhaps, via deriving value from tracking users and being able to use the combined content for various analytics (including lately AI training).
[3] Potentially reducing the cost/complexity of integrating disparate systems⁴, themselves.
[4] Sometimes in-house developed systems that might distract key devs from the company's products/services that they can sell.
My (not-so-actuarial 1990's-experience-colored) feeling is that this is Microsoft doing what Microsoft does best, namely including a lot of seemingly compelling features in a product to get people hooked and to keep competitors in a position of trying to keep up.
Having been through a couple of acquisitions (as a cog in the machine being acquired, not a founder or purchaser or such), the last one at the end of 2025, and seen others as an unofficial close observer via friends/family, I think this is quite normal. No matter how thorough the due diligence and other investigations are pre-purchase, there will usually be an information gathering time before any significant changes are made. Even without that there are a couple of months being very careful not to rock the boat too much, so as to not put the willies up shareholders and key human resources. The first significant changes often won't happen for 3-to-6 months, unless part of the reason for the acquisition is that the company was on the verge of failing or was growing too fast to cope. During that time, unless key people jump ship early forcing change to an extent, things below certain management levels are much more business-as-usual than you might expect.
(Github did probably want a native CI implementation but I'm not really sure Actions was the way to do it. It seems so needlessly complex to me, not to mention the massive security issues. The rest of those features are just far from something I'd ever use so I don't even really know how to comment on them)