It's probably not surprising that it happens. But still, Facebook has promised not combining any Whatsapp userdata and respecting users' privacy when they were taken over[0], and Facebook getting a €110.000.000 fine from the EU for breaking that promise three years ago [1].

[0] https://blog.whatsapp.com/setting-the-record-straight [1] https://ec.europa.eu/commission/presscorner/detail/en/IP_17_...