> Rust designed specifically for being a language for developing a rendering engine

Rust was born at Mozilla, sort of. It was created by a Mozilla employee. The first "real" project to put it into action was Servo of which parts were adopted into Firefox. While Rust may not have been developed "specifically" to create a browser, it is a fair comment.

That said, Ladybird was started as part of the SerenityOS project. That entire project was built using C++. If the original goal of Serenity was to build an opeerating system, C++ would have felt like a reasonable choice at the time.

By the time Ladybird was looking for "better" languages than C++, Ladybird was already a large project and was making very heavy use of traditional OOP. Rust was evaluated but rejected because it did not support OOP well. Or, at least, it did not support integration into a large, C++ based, OOP project.

Perhaps, if Ladybird had first selected a languge to write a browser from scratch, they would have gone with Rust. We will never know,

We do know that Mozilla, despite being the de facto stewards of Rust at the time, and having a prototype web browser written in Rust (Servo), decided to drop both Rust and Servo. So, perhaps using Rust for browsers is not as open and shut as you imply.

I stand corrected, I was always under the impression that Rust was created specifically for Servo; TIL.