There is no guarantee from companies that your data is secure, even if they say it is. Facebook and WhatsApp are the most popular examples.
To avoid this, the only way is to create your own server at home or at least your own server from a VPS provider.
As Reuters reported,
Google already has a vast stores of data it uses to market to people, everything from what they read online to what they watch on YouTube, to where they go using Google Maps. The deal would give the advertising giant a treasure trove of information about everything from how well Fitbit's 27.6 million users sleep at night, to when and how they exercise.
I don’t understand why all the tech press stories today talk about Google’s acquisition of Fitbit as a hardware acquisition. Why are they being so naive? This is a data acquisition. It’s about the data. That’s why Facebook was trying to get Fitbit instead. #hellnonotmydata
— Jen Simmons (@jensimmons) November 1, 2019
It is important to understand that this is not just Google. Facebook, Amazon, Apple, Microsoft...... all of them are playing the same or similar game.