So what I think -but again, not a lawyer- is that the previous version also didn’t grant Mozilla ownership of your data. For example, maybe there was already a legal limit to what rights the ToS can transfer to Mozilla, and the new version just re-iterates the existing law?

Well, it will always be there as long as Firefox is also there.

The post sounds like it the initial terms weren’t thought to be broader than the current ones, but that that apparently wasn’t clear when they were read by regular people. As a non-lawyer, it seems entirely possible to me that the legal ramifications of both versions are the same, as often things that will read one way to me, turn out to actually mean more specific things in a legal context.

Could some savvy code-reader go through it to see if something about the data collection has changed?

Yeah, I think it’s telling that it’s been a while now and nobody has pointed to any suspicious code.