due to dependencies and things like that, the source will have IFDEFs that basically exclude old x86 from every feature
This is complete nonsense, x86 is far more widely supported than ARM in libraries.
The other poster is right, this is a financial benefit to Apple to abandon their users, much like Microsoft did with Windows 11.
A lot of supply chain attacks are compromised user accounts. So its not uncommon for that user, or someone else involved in the project to recognize an unexpected release. Generally it also gives a chance for security companies to detect malicious code.
Ironically of course it also slows down adoption of security fixes so as a developer you'll need to monitor for important disclosures.
You mean you didn't *know* she was off making lots of little phone companies?