Mozilla is quite clear about that. They consider Firefox as a political (yeah privacy is a political stance) product like another. A costly one.
Basically the opposite of this pro censorship Mozilla stance.
At this point, even the awareness of recommendation bubbles and their shape & size can help quite a bit. It's a valid research.
It grates me that Mozilla seems to take very one-sided view on the politics of it, but hey, it's a start. Hopefully others will follow to counter-balance the Mozilla's slant.
I don't see how you could not have a "recommendation bubble" as long as you have recommendations. Even if they were to be 100% manual it's still a bubble of some kind.
Not only that, you effectively have these bubbles outside the internet too. A book will recommend further reading, friends will recommend certain things and so forth. There's no escaping it.
When I go to the YouTube homepage these recommendations are absolute junk. Links friends send me are much more relevant and influential.
IMO the most charitable reading of this initiative is that they believe the algorithm is somehow biased towards exposing and warming people to harmful content in an unobvious way.