Mull (from the DivestOS developers)

But nowadays I’m using a Chromium based browser on my phone because Firefox on Android doesn’t support process isolation

It would be great to hear the implication of that

Here you can find a good explanation on that.

It would still need an Android system/kernel exploit to further escape the system sandbox. It is an important hardening feature, but the browser isn’t completely insecure without it

So what? You can go back to firefox for that reasoning unless you are a very very high target

Did you read the sentence before that? A malicious website could read data from other websites(opened in different tabs), and also passwords stored in the browser, etc… There is no additional system exploit needed for that