there’s no user behaviour tracking

I mean, that depends on how you define user behaviour. It tracks which packages are frequently installed, for example, or how often people install Ubuntu in the first place. All of which I think is pretty legit, in my opinion, since that only involves aggregate user statistics that help prioritise work and detect common problems - but that’s essentially what Firefox is doing too.

Debian is a great example of relatively commonly used free software that doesn’t really collect data btw.