Vivaldi Browser

Searching for "Brave controversy" should bring up some of them. Basically over the years they've done various controversial things like enabling bitcoin mining by default, automatically including referrals in search or substituting their own ads. There was another much more recently, but I forget what that was. In the past, these controversies were followed by the CEO going on a marketing campaign and speaking to users on social media - the new users typically drowned out the controversy.

They're not a massively evil company, but my general impression is that they're very fickle and it would only take a relatively small sack of money for them to sell their users up the river.

Edit: I should also add that some of these things were added with little to no announcement. They were caught doing it the link referrals stuff, it wasn't included in the update changelog.