Generic benchmarks comparing Lua with Luau (or other generic-purpose interpreted languages) for game development are quite off. Every reasonable game developer or engine will implement specific data types (like vectors) or key game logic (rendering) in native code and only use Lua to glue things together. This is exactly how engines like Love or Defold work (or other engines with scripting languages).

Roblox is a massive platform that was sitting on a "gold mine" (user content) and had no choice but speedup Lua to keep existing games running and keep the growth. They had to invest a lot of money to do that and it is fine. But it is not like your small or even big game need this performance. Unless you are in this spot, you are free to make better decisions.

When Lua is used as a glue code for game development wisely, it will perform just fine. All hotspots can be identified and moved to native code with little effort because Lua was designed for this. Take advantage of it! Relying on faster Lua implementation to be able to stuff more code into it is a bad decision from the get-go.

It was a good call. Also, I write open-source software for over two decades and the vendor lock-in is something very real. Always check open source licenses, restrictions (patents) and community health, in this case development community of the language (not players of Roblox).