I think the key points are in section 2.3 of the terms (https://zed.dev/terms). "Certain versions" of the editor are open source.
So the source on GitHub looks to be available under the licences you've spotted, but perhaps the downloadable binaries from the main website contain additional code that isn't open source.
Technically we did abolish the monarchy back in the 17th century, but the replacement was so bad we brought them back about 10 years later, which I think makes us a minority of one and even more weird.
Anyway, back on topic: this is a ridiculous law that is forcing services to erode their security while smart criminals can just use some nice free open-source software somewhere else for E2E communication. And a lot of this is definitely down to lawmakers not understanding technology.
So the source on GitHub looks to be available under the licences you've spotted, but perhaps the downloadable binaries from the main website contain additional code that isn't open source.