Lack of transparency
For the analysis of behavior, personal data such as:
IP address (e.g., 192.168.178.11)
Referrer URL (the address of the page from which the visitor came)
Operating system info (the software that enables your computer to operate.
Cookies, if applicable
Mouse movements and keyboard strokes
user device settings (e.g. language settings, location, browser, etc.)
forwarded to Google.
Website users are usually not at all aware that they are being monitored in the background. Google also keeps a low profile about what data is collected and how it is used.