I'm an open source advocate. I used firefox for decades, even when it was being blown out of the water by Chrome performance wise. Recently I've switched to Brave due to many websites not rendering correctly or running slowly. Lots of government websites don't work with firefox for instance. You'll get decently far along in the form of a street parking permit, and then you can't submit it for some reason.
I wish Mozilla chose to pursue making the best browser engine possible. It's a winning strategy as we can see from the dominance of chromium based browsers. Instead they've tried adding features or products paired with the browser as their strategy. Some, such as containers, are great. Others, like pocket, are forgettable.
I'm also not a fan of how the CEO has been increasingly rewarded even though the market share has plummeted. At a certain point you need leadership to commit to improving market share and hold them to it. However, this has nothing to do with why I've switched browsers.