Generated js files provide stubs for that(and probably any other missing\stubbed) functions, and it puts it to global scope, capturing memory and wasm code instances, creating memory leaks.
That happens within audio worklet, for example, with this flags used for compilation:
set(EMSCRIPTEN_COMPILE_FLAGS "${EMSCRIPTEN_COMPILE_FLAGS} -O2")
set(EMSCRIPTEN_COMPILE_FLAGS "${EMSCRIPTEN_COMPILE_FLAGS} -mnontrapping-fptoint")
set(EMSCRIPTEN_COMPILE_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -mnontrapping-fptoint")
set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s MODULARIZE=1")
set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s EXPORT_NAME=\"'lyrebird'\"")
set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s EXPORT_ES6")
set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s ENVIRONMENT=web,worker,shell")
set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s POLYFILL=1")
set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -O2 --embind-emit-tsd hello.d.ts -s SINGLE_FILE")