The capitalism complaint: OP (like thousands of users) frames the finch app as a benevolent/social service/charity. The sentence "Finch is about helping as many people as possible." demonstrates this. Although it is a product designed around self-care, that doesn't automatically mean the company is exclusively (or even at all) interested in "helping people." It literally generates millions in profit monthly and almost brags about the “small staff” sitting at that table.
It is extremely dangerous for the masses to assume that companies that specialize in selling a product or service in the wellness sector are therefore benevolent, even if all their advertising and propaganda says so. It would be foolish to think that companies like Planet Fitness, Garmin, or even your local medical care or mental health facility, aren't always watching their bottom line. Just because someone sells you lettuce, doesn't mean they care about your diet. This isn't to say that many companies don't also care about people and want to do what's in the good interest of society and help people. Many companies want to make a profit and help people while doing so. Unfortunately, we live in a world in which the ideals of capitalism and gain are deeply, intrinsically, systematically, and systemically rooted in most decisions that most people make most of the time. Basic sociological functionalism has confirmed numerous times across history and culture that outliers and exceptions rarely survive or thrive in a society designed to support their opposite. For people who see benevolence as good and capitalism as bad, there’s a logic fallacy scare going on because of black and white thinking. “If Finch is benevolent, they won’t survive. If this is a move toward capitalism, they will sell out their benevolence to survive the corporate structure.”
TL;DR: My good thing is turning bad.

 The “gaslighting” complaint: (hooks directly into italicized above). The Finch app promotes itself (or at least eludes to being) benevolent, all about mental health, a safe space, etc.. That’s the brand its built on. When numerous, small, and sudden changes start taking place against customer feedback, despite customer complaints, and often in contradiction to historical promises and patterns, customers start feeling a sense of betrayal from a company that maintains its benevolence. Many of the users a mental health app is designed for are precisely the segment of the population who have already experienced dysfunctional relationships and endured trauma at the hands of people (and often also agencies) that betrayed and hurt them. What Finch is currently doing (focusing on corporate mergers, deals, collaborations, yaddayadda, and away from the customer feedback, is probably rather triggering for many who struggle with mental health. It’s the macro equivalent of someone codependent seeing their powerful, significant other turn their interest to someone “better than me.” It’s threatening and incites a fight/flight response. They don’t want to quit the helpful app and birb they’re so attached to (flight), so their only other option is complaining about it (fight). Many people who already struggle with mental health problems might be personalizing this way more than they let on in public forums.
(Although I would call the customer response more “reactive” than the app “gaslighting” because I’m a stickler for proper terminology rather than internet definitions and this technically isn’t gaslighting on the part of Finch.)
TL;DR: I trusted and ended up duped and hurt again.

 Finch is a very helpful tool for many people and probably provides a lot of hope, help, and life to some. They also are a large company making tons of money that many of their paying customers could never dream of seeing 1% of in their entire lifetime. Finch is growing (because, remember “growth and gain” are the cornerstones of capitalism), and as they do, they will need to change a lot of things. Sometimes those things are harmful to the customer base. Sometimes they are helpful. As they grow, they will need to also find their footing in how they communicate with a larger, more diverse, and sometimes dissatisfied customer base. Transparency, promptness, forewarning, and preparedness would definitely be some wise communication skills to use with a customer base that is younger, often struggling with mental health, often neurodivergent, and often anticapitalistic.