> This is what happened e.g. with chrome. There's chromium, anyone can build it. But that's not chrome. And chrome is what everybody uses because google has lock-in power.

Because Google has their attention. You can use chromium, but most people don't and pick the first thing they see. Also, Chrome is a much better name, err, not better but easier to say.

> Then google says "oh I'm going to disallow you running the extensions you like, so we can show you more ads". Then they make tweaks to chrome so that websites only get rendered well if they use certain APIs, so now competitors to Chrome are forced to implement those APIs, but those aren't public.

You and I have a different definition of "forced". But, are you speculating this might happen, or do you have an example of it happening?

> And all of this was initially build by free labour, which google took, by people who thought they were contributing to some commons in a sense.

Do you have an example of a site that works better in chrome, than it does in chromium? I'll even take an example of a site that works worse in the version of chromium before manifest v2 was disabled, compared to whatever version of chrome you choose?

> Copyleft licenses protect against this. Part of the license says: if you use these licenses, and you make changes to the software, you have to share the changes as well, you can't keep them for yourself".

Is chromium not still foss? Other than branding, what APIs or features are missing from the FOSS version? You mentioned manifest v3, but I'm using firefox because of it, so I don't find that argument too compelling. I don't think FOSS is worse, I think google is making a bad bet.