There is. As per the latest announcement from DivestOS:
DivestOS and its apps will not receive any further updates.
Sadly, that means that there is basically no privacy-respecting Firefox-based Android web browser as of now which works out-of-the-box.
There is IronFox, a Mull fork, but it remains to be seen whether they are trustworthy and can keep up with the updates. In the meantime, a hardened Fennec is probably the best we can do.
Looks good so far. But it remains to be seen whether the maintainers prove to be trustworthy and can keep up with the updates.