It's also a for-profit company and you're not the customer, as you're not paying them money.
I'd be way more worried how they're using the data they're collecting on you vs Google or MS
I used to recommend Firefox, but Mozilla has totally jumped the shark (privacy violations [multiple], wastes too much money, blocks APIs that are useful with no real security risks while approving APIs with little use that do have security risks, etc, very user hostile).
Chromium is obviously not trustworthy at this point, let alone Chrome. So that leaves like, Safari and Opera?
Brendan Eich is the CEO of Brave, and I trust him. Mozilla was good until he was ousted for political reasons.
Brave is like 99% of Chromium + uBlock…
Chromium is a great browser, unfortunately the official branch has been poisoned by Google.