That "integration with the browser’s garbage collector" feature in the webassembly roadmap doesn't mean the inclusion of a GC - it means there will be a mechanism by which a WASM-implemented GC can cooperate with the browser GC.

(There seem to be additional long term ideas int he wasm design repos for adding more GC support, but they seem vague at this point and it's not clear how interested browser vendors or language implementors are)