This is because of how Health Check categorizes 'trackers'. If you're new to Health Check, but you've used older versions of CCleaner for Windows, the tracker count may look much higher. This is because of the way Health Check categorizes data that tracks your online activity. The next section What does Health Check categorize as a tracker explains this in more detail.
What does Health Check categorize as a tracker?
How do you choose which trackers Health Check cleans?
When you analyze your PC with Health Check and reach the screen called Your PC feels under the weather, clicking the Privacy icon reveals the screen shown in the screenshot below.
If you don't want Health Check to clean a type of tracker, click the blue checkbox next to a specific tracker to uncheck it.
Should you worry about a high tracker count?
In short, you don't need to worry. You're likely to collect more trackers the next time you use the internet, depending on which web browser you use and the privacy settings you've activated.
Your two main concerns with trackers are your online privacy and the space these types of files can take up on your hard drive. In either case, clearing them out with CCleaner once a week is fine, especially after completing data-sensitive online tasks such as banking, etc.