Damn it would be nice if this meme would die.
The first of its sins is the tacit agreement that Mozilla is doing this because, as the parent comment says, they "need funding". Mozilla needs funding now like Wikipedia needs funding: they have more of it than they've ever had, but by all appearances, you'd think they're really strapped for cash or something, because their pleas have gotten steadily more intrusive and desperate.
Second is the "focus on their core product" remark. There's so much wrong with this sentence. First, it's the tacit acceptance that Mozilla is and should be a classic Valley tech company—a bit player with a product competing in the market, rather than the way mozilla.org operated in its heyday—you know, when it was actually a force for good and were winning hearts and minds. This is another case where the trend does not support the thesis. Mozilla _has_ steadily gotten more focused on Firefox compared to its historically diverse interests (to the exclusion and chagrin of many of its volunteers and advocates), and by most measures we're worse off for this Corporation-centric mindset. At its height, Mozilla was accomplishing way more, had greater influence than it has today, and did it on a fraction of the budget. Today, Mozilla has half a billion in annual revenue but the Firefox team claims that keeping a menu item around that lets you jump to a site's RSS feed is too much of a maintenance burden.
Where do you think all the money is going? It's not Thunderbird or developer.mozilla.org that are sucking hundreds of millions away. And as bad as Mitchell's leadership has been over the last 5+ years, her new salary in the low single-digit millions has pretty much nothing to do with it. For comparison, Mozilla has something like a 50+ million dollar marketing budget. This is classic cost disease. Ten years ago, it was a common quip that Chrome's effective marketing budget (i.e. in imaginary dollars) was greater than Mozilla's entire annual revenue. Well guess where we are today? A well-funded contender in the browser wars could almost certainly appear tomorrow and grab as much market share in the next 3 to 5 year period as Firefox currently has and do it on total operating costs that measure half of Mozilla's marketing spend (in actual dollars).
So please stop doing this. Every time you feed into this meme that you heard on social media and that sounded good to you because it wrapped things up in a nice, simple narrative, at best it's going to have no effect, and at worst you encourage Mozilla to lean in and do _exactly_ the things that have led to present situation. If you want to provide encouragement, encourage Mozilla to overhaul its entire leadership, to live by the principles they purport to care about (how about starting with removing opaque clicktracking links from emails?), to put a real content blocker in the browser, to stop hawking VPN snake oil, and to open source Pocket like it was promised over 4 years ago. Demand that they make falsifiable claims that can be evaluated for success or failure on well-defined criteria. Campaign for them to either cap the marketing budget to $1 million or actually do something effective with it (like writing a check to Wikimedia and then blogging about how the reason that there are no overlays on Wikipedia this year nagging you for funding this year is because Mozilla decided to foot the bill and so you're welcome—which would be way more effective than _anything_ the marketing department has done to date).