I agree with you that private APIs should be off limits, particularly to the author of a library which has broad use. But at this point, Apple's previous inactions sent the wrong message and by acting on this now with zero grace period a lot of developers are left in the lurch. Whether you want to point the finger at Electron or Apple doesn't matter, Apple has the opportunity to make developers lives easier here and instead they are just indifferent to it which is frustrating.

From reading the issue on GitHub, I see that there was a failure, then it started working, then two months later it started failing again.

I suspect there was a two month grace period. The problem would be that they gave that grace period to a developer (like Slack) rather than working with some Electron framework team.

I also suspect a reason the tools were revised to reject apps with use of these internal functions is that some of them are going away in March.

> I also suspect a reason the tools were revised to reject apps with use of these internal functions is that some of them are going away in March.

This is the thing, there are good reasons Apple should reserve certain libraries as private and not support them. The fact that Electron dipped into private libraries and didn't have a fallback plan for WHEN Apple clamped down on this is just poor planning. That said... a small amount of communications and/ or tolerance from Apple would go a long way towards developer good will here. Lots of small developers getting burned here.