Every few months there's something new coming up about that browser. Here's a non-exhaustive list of shady stuff:
- Manipulating search results to show ads
- Releasing Pay-to-surf with extensive tracking
- Blocking ads from companies only when they haven't paid them not to
- Gathering data about other installed browsers
- Crypto scam (yes, it was a scam, they stopped doing payouts)
- Profiling user habits and selling that data to advertisers
- Buying reviews
Of course, there's more.