Earlier quoted context omitted.
No, SerenityOS is strictly C++
Which is both very impressive given everything that is being produced, but also a bit scary and sad in 2022. There is ample evidence that even very excellent developers and teams can't avoid the footguns of c++ and that leads issues down the line. If we just look at the browser, they seem to make much faster progress than Servo, but there is no doubt it will have security flaws.
Use after free, double free, invalid stack RW, uninitialized data, race conditions, etc. They're all possible to be found in Zig programs, because the language doesn't provide assurances against them.