There's nothing "open core" about Microsoft shipping binaries with telemetry.
I paid for my Android phone. Google is still collecting every piece of my life and my family's.
A bit more seriously: there are shades of grey. Just because they gave you something for what you paid doesn't mean it was a) fair, nor b) what was (effectively) advertised. Legalese around "you really just bought X" doesn't necessarily put everything in the clear.
i.e. when you buy an Android phone, it seems reasonable for people to expect that to come with a functioning Android-based OS. Just because you can install a different OS on it doesn't mean the default one isn't subject to criticism.
Even those who purchase hardware where the bootloader can be unlocked, it takes much deeper technical knowledge to install a third party OS than, say, a third party OS on a PC. And that is assuming someone else built the OS for you.
I don't think all the telemetry is particularly useful, but there is no reason to give MS the benefit of the doubt here.
Outside of the paid part, that's precisely what Microsoft is doing. MS publishes a couple of proprietary extensions for VS code.
VSCode does not work at all for me without the "Remote SSH" extension. And the "Remote SSH" extension is proprietary and DRM-ed to be not work with the open source code.
I don't see how I'm stretching what "open core" means. This is just like any other open core stuff.
"Paid for" part, yeah you are right. I thought the orange site all agree I paid for Gmail, just not with money, but turns out I'm wrong.
I don't get what telemetry has to do with open source? It's entirely possible to ship a binary that is 100% "open source" - that is reproducible from OSS code - but still has telemetry.