Everyone's confused because of the missing chapters, so here's an explanation
Basically, the app(? company? agency?) distributing Spy X Family is Shueisha and unlike most manga in mangadex, shueisha is a legitimate source of manga (not fan scanlations) the mangas they distribute are under a licsence and because of this, they have to limit what chapters are available for the viewers to read for free. currently, they show the 3 most latest chapters of every series before removing them. They do this to encourage the readers to buy the original mangas, and in turn would help support the mangakas
I hope this answered some questions