It is not clear to me (I have not bothered to dig that much and I don't use either service), but it would appear that #facebook or #meta or whatever it is call today have implemented a requirement to identify with an account on "facebook" in order to use the #whatsapp service on the web*

This kind of action on their part is to be applauded fervently!

Any and every move that might persuade even a small amount of people to consider using any of the far superior messengers out there is to be welcomed.

If even just one more person abandons meta platforms, then today was a good day for humanity. If that person happens to be in #Mexico, all the better, as #whatsapp absolutely has Mexico by the balls.

So.... Well done Facebook, More of this kind of thing!

* There is a redirect happening, it is initiated presumably by some JS (obfuscated) running on web.whatsapp.com.

The login link on the facebook service, includes a parameter called "next" set to point back to whatsapp web. So from this one could assume that the redirect is intentional.