Generally, there aren’t any privacy concerns when using the Matomo Tag Manager per se.

However, depending on which tags you use, privacy can become an issue as you might send personal data to Matomo Analytics or third party providers. For example, if you use the “Facebook Pixel Tag”, then this may cause personal data to be sent to Facebook.

If you are using Matomo Tag Manager only to configure the Matomo Analytics tracking code, then there is no privacy disadvantage over using the Matomo Analytics tracking code directly.

Previous FAQ: Benefits and drawbacks of a tag management system (TMS)