It serves unbundled for development and bundled in production. In practice this works pretty well as long as you do decent code splitting (and you should be doing code splitting!)

Edit: lol I should have read your post more closely. Yes, the different strategies can cause bugs; there's much more shared between the two pipelines than there used to be so this situation is improving. We actually had really bad compatibility with problems six months ago and it was still easily worth the trouble for the performance improvement.