They have compiled to WASM64, the newer 64bit version of WASM. That's not available on iOS yet.

WASM till recently has had a 32bit address space, to match the limitations of JS numbers. With 64bit WASM you have to use BigInt rather than the floats that are numbers in js to address the memory.

It's only the address space that's affected - old WASM still handled 64bit math fine.