Another thing that would make 1 happen even if they think they're not leaking information over different channels, is the software keyboard. GBoard is google's,

Another thing that would make 1 happen even if they think they're not leaking information over different channels, is the software keyboard. GBoard is google's, and likely has some data collection in one way or another. Similarly, there's a lot of google-related services running with root privileges on stock android phones that could easily snoop on data from various apps. This effect is worsened by other android OEMs, like xiaomi or maybe even samsung, who ship their own invasive services on top.