They assumed that removing their last distinctions from chrome - the extensions that had become integral parts of the workflows of millions for up to a dozen years, and the lack of tab processes - would somehow get people to switch from chrome instead of to chrome in resentment. This was where the organization had fixed all of their hopes - once they got rid of extensions and got chrome's primary marked feature (on release), then they would stop hemorrhaging users, because now people could choose to have a browser that was almost exactly like chrome, just a little bit off, and a little bit slow on google-owned sites, but without google, and run by a non-profit.
Since this had no effect, except causing an instant loss of a lot of users (one that hasn't been completely felt yet due to esr), and a slight bump in chrome's user numbers, there's no resort other than advertise heavily the benefits of not using google's browser, without mentioning google negatively because they generally rely on google for funding. So just weird platitudes about "freer people web standard access foundation" or something. Or talk about start-up times that no one cares about, and which don't make them distinctive from chrome.
The immediate problem is the vast majority of people who are sympathetic to that branding were already firefox users, and at some point were turned off because firefox killed some plugin or other or it just stopped being updated, or because of some UI change which are now explicitly not mitigatable in quantum. The way firefox responded to those complaints (which is not materially, even once; when a meeting of firefox management has determined something is going to be done, it is going to be done, and exactly in that way) has assured that target audience that development by a non-profit is no more amenable to consumer desires than development by the largest, most predatory companies in the US. At least Microsoft and Google are big enough that user complaints catch fire in the mainstream media, and they're forced to respond to a critical audience. If firefox decides that they're going to take out the back button, because "in a modern internet, users shouldn't be moving backwards", you're just going to find a closed WONTFIX bug with 400 angry comments from users on it, and a few comments from Mozilla explaining how their user testing showed that people don't want a back button, the bug tracker isn't for general complaints, that the tone of the thread was very negative and regrettable, and that the thread was being closed for further comments.
The real problem is that Firefox has 10x as many employees as it needs, and is just another corporate bureaucracy collapsing under its own weight. Should have been slim and user-focused, and instead of rhetoric about a "free people web standard internet brings people together", central and visible in every conflict regarding the internet and its architecture, and the distribution of knowledge in general. It used to be almost that, but I think the fight over h264 broke it.
Now, the only reason it's alive is to keep the forces of antitrust from google's door.
Their employees, whether intentionally or inadvertantly, also brigade message boards.