This is the fictional hallucination that somehow makes it into every comment section about Mozilla. So let's go through the facts one more time:
(1) They spend more on browser development now than they ever have in their history even after adjusting for inflation.
(2) The majority of things claimed to be "money sinks" don't actually cost that much or siphon resources away from core browser development with some exceptions (we'll get to those).
(3) The market share losses happened from 2010-2015, the side bets era is approximately 2020-2025. The side bets didn't retroactively cause the market share losses.
(4) The narrative that a failure to keep up/push new features drove market share losses paints a picture that's entirely zoomed in on Mozilla and ignores Google leveraging its search and mobile monopolies to muscle its browser onto the map, which likely would have happened regardless of how good Firefox was.
(5) The narrative that the browser was broken and behind is somewhat outdated - it was true in the market share loss era, but then they did the dang thing and launched a major engineering effort, fundamentally rebuilt the major parts of the browser via Project Quantum, a monumental engineering transformation that delivered speed and stability, the thing everyone asked for. It's obviously not perfect, but in terms of performance and stability its certainly good enough to be a daily driver in most cases and not in a state of tragic disrepair.
(6) Despite it being supposedly so obvious, no one can explain what missing browser feature they can add that will restore all their market share overnight.
That said, yes, there are bad things: the dabbling in adtech is bad imo ("privacy preserving ads" seems to be category error), dabbling with AI doesn't seem to have an obvious point in its current iteration, Pocket was understandable as a revenue grower but seems have been a wash and annoyed users and they didn't bother to maintain it, Mozilla nonprofits broader advocacy for privacy seems to be confusing some people, and Firefox OS genuinely did seem to have cost engineering resources at a time that they lost market share. That said, I would love if there was a 10 year old Firefox OS project right now given Google's pushing of developer certification.
So, yes, there's stuff I don't love. I don't feel like this iteration of Mozilla has the innovative spirit of, say, Opera back in its heyday, and it's not as polished as Chrome. But the comment section rhetoric has spilled over into fever dream territory and not is even pretending to map onto any coherent historical timeline, factual record, or story of cause and effect, and often contradictory in its declaration of demands.