User ID (Google Analytics)
Как только клиент прошел авторизацию Analytics фиксирует его User ID. Он показывает конкретику о количестве пользователей, а не устройств.
google analytics
Client ID in Google Analytics
In Google Analytics, a Client ID is a unique identifier assigned to each browser-device pair that visits your website. It’s a randomly generated number stored in a cookie (_ga cookie for Universal Analytics or ga container ID for GA4) on the user’s device.
Sampling Data (Google Analytics)
Sampling is a way of sampling the data on which the reporting will be based.