Posting here because I need the character space...
If your #Android device is running #Google apps, your #Signal chats are generally not private. I just had a conversation topic that only came up once in a specific Signal chat show up in targeted advertising on #Youtube. The chat happened on another system, so it wasn't the phone's keyboard (which was swapped out from stock anyways). But the signal chat info showed up in a targeted advert just minutes after starting the Youtube phone app, which I rarely use.
Virtual keyboard had been swapped out already, so it wasn't likely a keyboard cache attack.
This behavior did not show up when using after-market Android operating systems like Graphene (or Calyx or Postmarket, etc). That is also because I usually run multiple segregated profiles, and Google apps have their own tiny little box there. This was my spare phone because my regular Graphene phone was inoperable at the time.
This isn't to throw shade on the excellent work Signal does, but to make very clear to people that the best way to keep things like this from happening is to use separate user profiles for app that aren't trustworthy. This isn't really possible for me with a $BigVendor phone that pre-installs a bunch of apps that you can't get rid of easily. Which is why the next couple of night will be spent installing CalyxOS on yet another pixel refurb.