Their definition of "the platform" in the TOS is verbose and has weird grammar. I can see how people came away with a different understanding.

> User shall not translate, decompile or reverse-engineer the Platform, or engage in any other activity designed to identify the algorithms and logic of the Platform’s operation, unless expressly allowed by Arduino or by applicable license agreements;

> The Site is part of the platform developed and managed by Arduino, which allows users to take part in the discussions on the Arduino forum, the Arduino blog, the Arduino User Group, the Arduino Discord channel, and the Arduino Project Hub, and to access the Arduino main website, subsites, Arduino Cloud, Arduino Courses, Arduino Certifications, Arduino Docs, the Arduino EDU kit sites to release works within the Contributor License Agreement program, and to further develop the Arduino open source ecosystem (collectively, the “Platform”).

I can only read this as the entirety of "Arduino open source ecosystem" being part of "the Platform".

I'm pretty sure that is the point. Legal ambiguity to say whatever they can vaguely in public but in court they will make it encompass the entire world.

> why was everyone up in arms?

Engagement farming, clout chasing etc.

Large companies have repeatedly demonstrated that they will pick whichever interpretation is most convenient at the time. When there are pitchforks they will claim that you are confused and misinterpreted the writing but when you get poisoned by food in their restaurant and try to sue them they will point at terms of service on their online video streaming service that your spouse agreed 5 years ago as if that's relevant (not a joke Disney tried that one). These things are supposed to be written by proffesionals, I dont think Hanlon's razor sufficiently explains it, terms of service are at least partially intentionally written as vague and unclear as possible for benefit of one side.

That's called motte and bailey.

u/healsdata already gave a good answer to that. I may only add that this could be the first step of increasing restrictions made by qualcom. The future will show. If it happens, some who warned about that may wisely nod their heads then, whereas others will be very confused about "this sudden change" ...